“Kata-Kana”character is a kind of phonetic characters for the Japanese language transformed from the Chinese character. The scientific study on the history of“Kata-Kana”characters was originated by Dr. Tohru Ohya from the beginning of the 20th century. He was the first scholar who took notice of the“Kunten”materials of the Heian-period as very important and useful manuscripts to research the history of the Japanese language. These“Kunten”materials have been kept in several old traditional temples, and offers many reliable proofs on the invention of“Kata-Kana” characters. After Ohya, Professors Shinkichi Hashimoto, Masaji Kasuga, M. J. A, and Norio Nakada have had the outstanding achievements in this field. However, many problems are left unsolved. The facts philologically proved for the present are as follows. “Kata-Kana”characters were devised in the early 9th century by the Buddhist scholars (especially studying at Todaiji (_??__??__??_) Temple), in order to express the Japanese reading of the Chinese sentences. The scholars had to write down the Japanese reading in the narrow space between the lines of the Chinese sentences, listening their teacher's lecture. “Kata-Kana”characters were formed by abbreviating the strokes of Chinese characters, leaving the first strokes or the final strokes of them, for the purpose of saving these time and labour. In the first period of inventing“Kata-Kana”characters, many different forms were used at the same time with“Mannyou-Gana”, and“Hira-Gana” characters which was made from the cursive style of the Chinese characters, but, in the phase of reading Chinese sentences, “Kata-Kana”characters had taken more simplified forms and had been standardized in the society by 12th Century. The current forms of“Kata-Kana”characters today have been officially settled in 1900 by the Japanese government. “Kata-Kana”characters were made from Chinese characters which had been used especially as“Mannyo-Gana”in the ancient Japan. Accordingly, the explanation that“Kata-Kana”_??_ (sa) was abbreviated from _??_ or _??_ is not right, because these Chinese characters had never been used as“Mannyo-Gana”. This theory may be revised to be from _??_. As these characters were made for the purpose of quick writing, the origin is not formal style but simplified style. _??_ (re) and _??_ (ne) are not from _??_ (rei) and _??_ (nei), but from simplified style _??_ andi _??_. _??_ (we, e) is not from _??_ (we) but from the beginning part of curved strokes of _??_ (we). Beside these facts, the origins of the“Kata-Kana”characters used in the present time are often misunderstood generally. For example, “Kata-Kana” character _??_ (ta) is explained as to be formed from the beginning strokes of Chinese character _??_ (ta), but it is not right. It is from its last stroke, according to the ancient form _??_. _??_ (ro) was not from _??_, but from _??_ which was the old form of this character. “Kata-Kana”characters have kept essentially a phonetic and practical factor through their history. They have never had an aesthetic factor, different from“Hira-Gana”characters. “Kata-Kana”characters have made historical change by reason of practical usage, although some unique and curious forms used exceptionally in some sects of Buddhism and Confusiasm in the Heian period had been bequeathed to the after ages.