The general contents and the epoch of calendar of Tae-t'ong-ryok-il-t'ong-kwe, T'ae-yang-t'ong-kwe, T'ae-um-t'ong-kwe, Kyo-sik-t'ong-kwe, O-song-t'ong-kwe and Sa-yo-chon-to-t'ong-kwe were investigated and compared with each other. These books were written by Yi Sun-chi and Kim Tam on the basis of either Su-si-ryok or Tae-t'ong-ryok during the period of King Se-jong in the Choson dynasty. Su-si-ryok from Yuan and Tae-t'ong-ryok from Ming are all the same in contents, but the epochs of them do not coincide. The epochs of Tae-t'ong-ryok-il-t'ong-kwe and O-song-t'ong-kwe were referenced based on Su-si-ryok and the epochs of other books were corrected based on Tae-t'ong-ryok. In addition, it is presumed that the six series of T'ong-kwe were written in the process of preparing for the compilation of Ch'il-chong-san-nae-p'yon.