diff --git a/src/保育・教育日数マスタ/main.css b/src/保育・教育日数マスタ/main.css
new file mode 100644
index 0000000..b62ae36
--- /dev/null
+++ b/src/保育・教育日数マスタ/main.css
@@ -0,0 +1,77 @@
+#legend {
+  width: 100%;
+  top: -24px;
+  position: absolute;
+  text-align: right;
+  font-size: 13px;
+}
+
+#legend .box {
+  display: inline-block;
+  width: 14px;
+  height: 14px;
+  background: #ffe3e6;
+  margin-right: 4px;
+  vertical-align: middle;
+}
+
+/* カレンダーエリア */
+#calendar {
+  width: 100%;
+  height: 100%;
+  display: grid;
+  grid-template-columns: repeat(3, 1fr);
+  grid-template-rows: repeat(4, 1fr);
+  gap: 12px;
+  box-sizing: border-box;
+}
+
+.month {
+  display: grid;
+  grid-template-columns: repeat(7, 1fr);
+  grid-template-rows: auto repeat(6, 1fr);
+  border: 1px solid #aaa;
+  border-radius: 4px;
+}
+
+.month .title {
+  grid-column: 1/8;
+  text-align: center;
+  font-weight: bold;
+  padding: 4px 0;
+}
+
+.month .cell {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 13px;
+}
+
+#calendar:not(.readonly) .month .cell:not(.header):not(:empty) {
+  cursor: pointer;
+}
+
+.month .cell:not(:empty) {
+  padding: 2px 0;
+}
+
+.month .sun {
+  color: #e74c3c;
+}
+
+.month .sat {
+  color: #2196f3;
+}
+
+.month .cell.selected {
+  background: #ffe3e6;
+}
+
+#calendar:not(.readonly) .month .cell:not(.header):not(.selected):not(:empty):hover {
+  background: #ffe3e677;
+}
+
+#calendar:not(.readonly) .month .cell.selected:hover {
+  background: #ffd3d7;
+}
diff --git a/src/保育・教育日数マスタ/main.js b/src/保育・教育日数マスタ/main.js
new file mode 100644
index 0000000..7eb1b61
--- /dev/null
+++ b/src/保育・教育日数マスタ/main.js
@@ -0,0 +1,312 @@
+(() => {
+    'use strict'
+    let _CALENDAR
+
+    // レコード詳細/新規作成/編集画面表示時にカレンダーを初期化
+    kintone.events.on(
+        ['app.record.detail.show', 'app.record.create.show', 'app.record.edit.show'],
+        (event) => {
+            kintone.app.record.setFieldShown('休日の生データ', false);
+            initCalendarArea(
+                event.record,
+                getHolidayMap(event.record),
+                event.type === 'app.record.detail.show'
+            )
+            return event
+        }
+    )
+
+    // 年度フィールド変更時に各月の休日をクリアしてカレンダーを再描画
+    kintone.events.on(
+        [
+            'app.record.create.change.年度',
+            'app.record.edit.change.年度',
+            'app.record.index.edit.change.年度'
+        ],
+        (event) => {
+            forEachRawFields((field) => {
+                event.record[field].value = ''
+            })
+            if (event.type !== 'app.record.index.edit.change.年度') {
+                initCalendarArea(event.record)
+            }
+            return event
+        }
+    )
+
+    // 一覧編集画面では各月の休日フィールドを編集不可にする
+    kintone.events.on(
+        ['app.record.index.edit.show'],
+        (event) => {
+            forEachRawFields((field) => {
+                event.record[field].disabled = true
+            })
+            return event
+        }
+    )
+
+    // レコード保存時にカレンダーで選択した休日を各月フィールドへ反映
+    kintone.events.on(
+        ['app.record.create.submit', 'app.record.edit.submit'],
+        (event) => {
+            const resultMap = _CALENDAR.getSelectedDatesMap()
+            forEachRawFields((field, i) => {
+                event.record[field].value = resultMap[i].join(',')
+            })
+            return event
+        }
+    )
+
+    /* --------------------------------------------------
+     * 初期化・データ準備
+     * -------------------------------------------------- */
+    // カレンダー表示エリアを初期化
+    function initCalendarArea(record, map = {}, readonly = false) {
+        const calendarAreaEl = kintone.app.record.getSpaceElement('calendar-area')
+        calendarAreaEl.innerHTML = ''
+        const year = record.年度.value
+        if (isYearString(year)) {
+            _CALENDAR = createCalendar(Number(year), map, readonly)
+            calendarAreaEl.appendChild(_CALENDAR.fragment)
+        }
+    }
+
+    // 既存レコードに保存されている休日を取得
+    function getHolidayMap(record) {
+        const res = {}
+        forEachRawFields((field, i) => {
+            const str = record[field].value
+            if (!str) {
+                return
+            }
+            res[i] = new Set(str.split(','))
+        })
+        return res
+    }
+
+    /* --------------------------------------------------
+     * ユーティリティ
+     * -------------------------------------------------- */
+    // 各月フィールドをループ
+    const forEachRawFields = (callback) => {
+        for (let i = 1; i <= 12; i++) {
+            callback(`休日_${i}月`, i)
+        }
+    }
+
+    // ゼロパディング
+    const padZero = (n) => (n < 10 ? '0' + n : n)
+
+    // Date → yyyy-MM-dd
+    const toYmd = (d) => `${d.getFullYear()}-${padZero(d.getMonth() + 1)}-${padZero(d.getDate())}`
+
+    // 土日判定
+    const isWeekend = (d) => d.getDay() === 0 || d.getDay() === 6
+
+    // 年度文字列の妥当性チェック
+    function isYearString(str) {
+        // 文字列かつ空でない
+        if (typeof str !== 'string' || str.length === 0) {
+            return false
+        }
+
+        // 数字のみ
+        if (!/^\d+$/.test(str)) {
+            return false
+        }
+
+        // 4桁
+        if (str.length !== 4) {
+            return false
+        }
+
+        // 1900-3000 の範囲
+        const year = parseInt(str, 10)
+        return year >= 1900 && year <= 3000
+    }
+
+    /* --------------------------------------------------
+     * カレンダー生成
+     * -------------------------------------------------- */
+    const createCalendar = (year, highlightMap, readonly) => {
+        const fragment = document.createDocumentFragment()
+
+        /* ----- 図例 ----- */
+        const legend = document.createElement('div')
+        legend.id = 'legend'
+        legend.innerHTML = '<span class="box"></span>休日'
+        fragment.appendChild(legend)
+
+        /* ----- カレンダーコンテナ ----- */
+        const calendar = document.createElement('div')
+        calendar.id = 'calendar'
+        if (readonly) {
+            calendar.classList.add('readonly')
+        }
+        fragment.appendChild(calendar)
+
+        /* ----- 内部状態 ----- */
+        const selectedSet = new Set()
+        const months = buildMonths(year)
+        months.forEach((m) => {
+            calendar.appendChild(buildMonth(m))
+        })
+
+        /* ---------- 月情報生成 ---------- */
+        function buildMonths(year) {
+            return Array.from({ length: 12 }, (_, i) => {
+                const monthIndex = 3 + i // 0 基準月で 4 月始まり
+                const date = new Date(year, monthIndex, 1)
+                return {
+                    displayMonth: date.getMonth() + 1,
+                    year: date.getFullYear(),
+                    month: date.getMonth(),
+                    label: `${date.getFullYear()}年${date.getMonth() + 1}月`
+                }
+            })
+        }
+
+        /* ---------- 月単位カレンダー生成 ---------- */
+        function buildMonth({ displayMonth, year, month, label }) {
+            const monthBox = document.createElement('div')
+            monthBox.className = 'month'
+
+            buildTitle(monthBox, label)
+            buildHeader(monthBox)
+
+            const first = new Date(year, month, 1)
+            buildPadBlocksStart(first, monthBox)
+            buildDateBlocks(year, month, displayMonth, monthBox)
+            buildPadBlocksEnd(monthBox)
+
+            return monthBox
+        }
+
+        function buildTitle(monthBox, label) {
+            const title = document.createElement('div')
+            title.className = 'title'
+            title.textContent = label
+            monthBox.appendChild(title)
+        }
+
+        function buildHeader(monthBox) {
+            ['日', '月', '火', '水', '木', '金', '土'].forEach((day, i) => {
+                const cell = document.createElement('div')
+                cell.className = 'cell header'
+                addWeekendClass(cell, i)
+                cell.textContent = day
+                monthBox.appendChild(cell)
+            })
+        }
+
+        function addWeekendClass(cell, week) {
+            if (week === 0) {
+                cell.classList.add('sun')
+            } else if (week === 6) {
+                cell.classList.add('sat')
+            }
+        }
+
+        function buildPadBlocksStart(first, monthBox) {
+            const startDayInWeek = first.getDay()
+            for (let i = 0; i < startDayInWeek; i++) {
+                const cell = document.createElement('div')
+                cell.className = 'cell'
+                monthBox.appendChild(cell)
+            }
+        }
+
+        function buildDateBlocks(year, month, displayMonth, monthBox) {
+            const last = new Date(year, month + 1, 0)
+            const highlights = highlightMap[displayMonth] || null
+
+            for (let day = 1; day <= last.getDate(); day++) {
+                const dateObj = new Date(year, month, day)
+                const ymd = toYmd(dateObj)
+                const cell = document.createElement('div')
+                cell.className = 'cell'
+                cell.textContent = day
+                cell.dataset.date = ymd
+
+                addWeekendClass(cell, dateObj.getDay())
+
+                // 初期選択判定
+                let shouldSelect = false
+                if (highlights === null) {
+                    shouldSelect = isWeekend(dateObj)
+                } else if (highlights instanceof Set) {
+                    shouldSelect = highlights.has(ymd)
+                }
+
+                if (shouldSelect) {
+                    cell.classList.add('selected')
+                    selectedSet.add(ymd)
+                }
+
+                // 編集可モードのみクリックイベントを追加
+                if (!readonly) {
+                    cell.addEventListener('click', () => {
+                        cell.classList.toggle('selected')
+                        if (cell.classList.contains('selected')) {
+                            selectedSet.add(ymd)
+                        } else {
+                            selectedSet.delete(ymd)
+                        }
+                    })
+                }
+
+                monthBox.appendChild(cell)
+            }
+        }
+
+        function buildPadBlocksEnd(monthBox) {
+            // 7×7 マスに揃えるための埋め草
+            while (monthBox.children.length < 49) {
+                const cell = document.createElement('div')
+                cell.className = 'cell'
+                monthBox.appendChild(cell)
+            }
+        }
+
+        /* ---------- 選択済み日付取得 ---------- */
+        function getSelectedDatesMap() {
+            const res = {}
+            months.forEach(({ month }) => {
+                res[month + 1] = []
+            })
+
+            // 選択済み日付を振り分け
+            selectedSet.forEach((ymd) => {
+                const d = new Date(ymd)
+                const displayMonth = d.getMonth() + 1
+                res[displayMonth].push(ymd)
+            })
+
+            // 選択が無い月は全土日を自動追加
+            Object.keys(res).forEach((monthKey) => {
+                if (res[monthKey].length === 0) {
+                    const monthInfo = months.find((m) => m.displayMonth == monthKey)
+                    if (monthInfo) {
+                        const year = monthInfo.year
+                        const month = monthInfo.month
+                        const lastDay = new Date(year, month + 1, 0).getDate()
+
+                        for (let day = 1; day <= lastDay; day++) {
+                            const dateObj = new Date(year, month, day)
+                            if (isWeekend(dateObj)) {
+                                res[monthKey].push(toYmd(dateObj))
+                            }
+                        }
+                    }
+                }
+            })
+
+            return res
+        }
+
+        return {
+            fragment,
+            getSelectedDatesMap
+        }
+    }
+})()
\ No newline at end of file