In bibliographic and authority data of materials in Japanese, it is necessary to represent kanji (Chinese characters) and its reading as a pair. Readings, called “yomi” in Japanese, are represented in katakana or the alphabet (romanization form). The readings in Japanese language have many variations depending on the context, so Japanese bibliographic information needs to provide both kanji and its reading as a pair to avoid misunderstandings.The JAPAN/MARC is a machine readable version of the Japanese National Bibliography and provides sets of kanji, katakana-yomi and romaji-yomi (romanization form) of bibliographic and authority data. This paper introduces how readings of bibliographic and authority data in Japanese have been expressed and handled mainly in JAPAN/MARC, compared with international standards.