仕組みと動作原理
ISNUMBER関数はExcel業務を効率化する代表的な関数です。Checks whether a value is numeric and returns TRUE or FALSE. 複雑な集計や参照処理を簡素化し、データ分析の精度と生産性を飛躍的に高めます。
構文.
標準Excel表記法=ISNUMBER(value)引数一覧.
この関数で指定できるすべての引数について詳しく解説します。
The cell or expression to test.
指定例:A2具体的な計算例
ステップ別の実務シナリオData Validation - Numeric Price Check
Check if entered price values are numbers or accidental text strings.
| Product | Price Input | Is Number? |
|---|---|---|
| Monitor | 249.99 | — |
| Keyboard | Free | — |
| Mouse | 29.95 | — |
=ISNUMBER(B2)Evaluates ISNUMBER over the sample table cells, placing the verified output in cell C2.
数式ジェネレーター
ウィザードを開く引数を入力するだけで、シートにそのまま貼り付けて使える数式を作成できます。
=ISNUMBER()出力される値の特性
Returns boolean TRUE based on sample evaluation criteria and active cell references.
実務上のベストプラクティス
- Nest inside FIND or SEARCH to test if text contains a specific substring: =ISNUMBER(SEARCH("corp", A2)).
- Dates and times always evaluate to TRUE in ISNUMBER.
よくあるミスと注意点
- Numbers imported from databases formatted as text strings (e.g. "1200") return FALSE. Use VALUE(A2) to convert them first.
各プラットフォーム対応表
実際のExcelおよびGoogleスプレッドシートの計算エンジン仕様に基づいた検証結果です。
Core standard function supported across all modern and legacy Microsoft Excel versions (365, 2021, 2019, 2016, 2013, 2010), as well as Excel for the Web and Mac.
100% compatible with Google Sheets. Uses identical argument order, data types, and standard calculation logic.
よくある質問と回答
技術解説Can I use ISNUMBER across different worksheets in Excel?↓
Yes. You can reference cells located on other sheets by including the sheet name followed by an exclamation mark, for example: =ISNUMBER(Sheet2!A2:A10). If the sheet name contains spaces, enclose it in single quotes: ='Q1 Report'!A2:A10.
What is the most common reason for errors in ISNUMBER?↓
Numbers imported from databases formatted as text strings (e.g. "1200") return FALSE. Use VALUE(A2) to convert them first.
Does ISNUMBER work identically in Google Sheets?↓
Yes, ISNUMBER is supported in both Microsoft Excel and Google Sheets with standard evaluation behavior.