The purpose of this paper is to consider (1) the difference between diacritical marks for Sino-Japanese used by Kiyohara Nobukata(清原宣賢, 1475-1550) and Kiyohara Shigekata (清原枝賢, 1520-1590), and (2) sound changes in diacritical materials(訓点資料). For this purpose I will deal with the Rongo(論語) and the Chuyo-Shoku(中庸章句). The following can be pointed out: 1) In Shigekata’s manuscript /zi/(ジ) and /di/(ヂ) merge under /zi/(ジ), /au/(アウ) and/wau/(ワウ) merge under /wau/(ワウ); 2) In Shigekata’s manuscript Goon(呉音) is more frequently employed than in Nobukata’s manuscript; 3). /-eu/ and /-jou/ are transliterated as -IYOU(イヨウ) in Nobukata’s manuscript and as -EU(エウ) in Shigekata’s manuscript. This indicates that language change came about between Nobukata’s...