{"id":660,"date":"2026-09-23T02:16:42","date_gmt":"2026-09-22T17:16:42","guid":{"rendered":"https:\/\/jim-jin.com\/?p=660"},"modified":"2026-10-08T09:10:02","modified_gmt":"2026-10-08T00:10:02","slug":"csv%e3%81%8c%e6%96%87%e5%ad%97%e5%8c%96%e3%81%91%e3%81%99%e3%82%8b%e5%8e%9f%e5%9b%a0%ef%bd%9cutf-8%e3%83%bbshift_jis%e3%83%bbbom%e3%81%ae%e9%81%95%e3%81%84","status":"publish","type":"post","link":"https:\/\/jim-jin.com\/en\/posts\/660","title":{"rendered":"Why CSV Text Becomes Garbled | UTF-8, Shift_JIS and BOM"},"content":{"rendered":"\n

Have you opened a downloaded CSV in Excel only to find that Japanese text becomes unreadable? It may display correctly in another application but become garbled in Excel.<\/p>\n\n\n\n

A common cause of garbled CSV text is a mismatch between the encoding used to save the file and the encoding used to read it.<\/strong> Even if the display is garbled, the original file is not necessarily damaged.<\/p>\n\n\n\n

This article explains UTF-8, Shift_JIS and BOM, terms often encountered with CSV files, and how to check settings to prevent garbled text.<\/p>\n\n\n\n

Garbled CSV text comes from mismatched decoding rules<\/strong><\/p>\n\n\n\n

Computers do not save Japanese characters directly as visible letters. They encode them as sequences of numbers and decode them when opening files. These rules are called character encodings.<\/p>\n\n\n\n

For example, reading a UTF-8 CSV as Shift_JIS may produce different characters or symbols.<\/p>\n\n\n\n

Encoding when saved<\/th>Encoding when read<\/th>Expected display<\/th><\/tr><\/thead>
UTF-8<\/td>UTF-8<\/td>Displays correctly<\/td><\/tr>
Shift_JIS<\/td>Shift_JIS<\/td>Displays correctly<\/td><\/tr>
UTF-8<\/td>Shift_JIS<\/td>Japanese and other text may become garbled<\/td><\/tr>
Shift_JIS<\/td>UTF-8<\/td>Japanese and other text may become garbled<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Letters and numbers may remain readable while Japanese text is garbled. UTF-8 and Shift_JIS share representations for ordinary ASCII letters and digits but differ for Japanese text.<\/p>\n\n\n\n

Also, the .csv extension does not identify a single encoding.<\/strong> CSV encoding depends on the application and save settings used to create it.<\/p>\n\n\n\n

How do UTF-8, Shift_JIS and BOM differ?<\/strong><\/p>\n\n\n\n

\"UTF-8,<\/figure>\n\n\n\n

UTF-8 and Shift_JIS are character encodings, while a BOM is a marker at the beginning of a file.<\/p>\n\n\n\n

JIM-JIN CSV Encoding Repair (Free)<\/span><\/a><\/div>\n\n\n\n
Term<\/th>Role<\/th>What it means for CSV files<\/th><\/tr><\/thead>
UTF-8<\/td>An encoding covering many languages, including Japanese<\/td>Used to exchange data with web services and other systems<\/td><\/tr>
Shift_JIS<\/td>An encoding mainly for Japanese text<\/td>May be required by existing business systems<\/td><\/tr>
BOM<\/td>A marker identifying an encoding or related information<\/td>Can help Excel recognize UTF-8 CSV files<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

UTF-8 files can have a BOM or no BOM. Both are UTF-8 and support the same range of characters.<\/p>\n\n\n\n

UTF-8: an encoding for Japanese and many other languages<\/strong><\/p>\n\n\n\n

UTF-8 is one way to store Unicode characters in files. It supports Japanese, English, Chinese and many other languages.Official Unicode FAQ<\/a><\/p>\n\n\n\n

Saving as UTF-8 does not guarantee correct display in every application. The reader must also decode the file as UTF-8.<\/p>\n\n\n\n

If a CSV provider states that the output is UTF-8, normally choose UTF-8 when importing it too.<\/p>\n\n\n\n

Shift_JIS: common in Japanese business data<\/strong><\/p>\n\n\n\n

Shift_JIS has long been used for Japanese data and may still be specified for imports into business systems.<\/p>\n\n\n\n

Note that Shift_JIS shown in Windows settings may refer to CP932, which has an extended character repertoire. Microsoft also describes code page 932 as a form of Shift_JIS.Microsoft’s code page documentation<\/a><\/p>\n\n\n\n

If a converter offers both Shift_JIS and Windows-31J\/CP932, check the destination’s requirements.<\/p>\n\n\n\n

Not every character supported by UTF-8 can be saved in Shift_JIS. Emoji or some kanji may cause conversion to stop or unsupported characters to be replaced.<\/p>\n\n\n\n

JIM-JIN CSV Encoding Repair (Free)<\/span><\/a><\/div>\n\n\n\n

BOM: a marker identifying UTF-8<\/strong><\/p>\n\n\n\n

BOM stands for Byte Order Mark. At the start of a UTF-8 file, it can signal that encoding to the reader. It is normally not displayed on screen.Unicode’s explanation of BOM<\/a><\/p>\n\n\n\n

Microsoft explains that UTF-8 CSV files saved with a BOM can be opened normally in Excel. UTF-8 files without a BOM can also be opened using Excel’s data import features.Microsoft’s official CSV import guidance<\/a><\/p>\n\n\n\n

However, some systems do not expect a BOM.Making a file easy to open in Excel and making it suitable for a destination system are separate considerations.<\/strong><\/p>\n\n\n\n

Simply adding a UTF-8 BOM to a Shift_JIS file does not convert it to UTF-8.<\/p>\n\n\n\n

Why can CSV text become garbled in Excel?<\/strong><\/p>\n\n\n\n

\"Why<\/figure>\n\n\n\n

Double-clicking a CSV skips the step of reviewing or specifying its encoding. Garbling occurs if Excel’s chosen interpretation does not match the file’s encoding.<\/p>\n\n\n\n

Behavior depends on Excel version, operating system and file contents. Rather than assuming Excel cannot read UTF-8 or all CSV files should use Shift_JIS, check import settings.<\/p>\n\n\n\n

Pay particular attention in these situations.<\/p>\n\n\n\n