仕組みと動作原理
LEFT関数はExcel業務を効率化する代表的な関数です。文字列の先頭（左端）から指定した文字数の文字を取り出します。 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。
💡 わかりやすい要約
Extracts a specific number of characters starting from the very beginning (left edge) of a text cell.
"Think of this like cutting off the first few letters of a word starting from the left side."
構文.
標準Excel表記法=LEFT(文字列, [文字数])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 text string that contains the characters you want to extract.
指定例:A2Specifies the number of characters you want LEFT to extract. Must be greater than or equal to zero.
初期値: 1具体的な計算例
ステップ別の実務シナリオExtract Country Codes
Extract the first 3 characters representing the country/area code from the phone numbers in column A.
| Phone Number | Full Name | Country Code | ||
|---|---|---|---|---|
| +1-206-555 | John | — | — | — |
| +44-20-794 | Sarah | — | — | — |
| +91-982-12 | Raj | — | — | — |
=LEFT(A2, 3)Evaluates LEFT over the sample table cells, placing the verified output in cell C2:C6.
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。
=LEFT()出力される値の特性
Returns "Calculated output" based on sample evaluation criteria and active cell references.
実務上のベストプラクティス
- Combine LEFT with FIND to extract all characters before a specific character (like a space or hyphen).
- If num_chars is greater than the length of text, LEFT returns all of text.
よくあるミスと注意点
- If num_chars is negative, LEFT returns a #VALUE! error.
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 LEFT 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: =LEFT(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 LEFT?↓
Does LEFT work identically in Google Sheets?↓
Yes, LEFT is supported in both Microsoft Excel and Google Sheets with standard evaluation behavior.