Copulation process, fertilization and gestation of the viviparous teleost surfperch, Ditrema temmincki were investigated by using photomicroscopy. Samples were collected from the vicinity of Suyoung Bay, Pusan, Korea from May 1992 to August 1993. During the copulation period, the copulatory organs were protruded at the base part of right and left soft ray of the anal fin in mature male. Secondary sexual characteristics index (SSCI) of male participated in copulation was above 3.5. Mature oocytes appeared only in the female containing sperms in the ovarian cavity. Transport of the spermatozoa into the ovarian cavity during copulation belonged to a spermatophore type. After copulation, spermatozoa remained in the ovarian cavity for about one month untill fertilization. Fertilization occured within the follicular cavity. Fertilized eggs were released into the ovarian cavity where they developed during gestation period. Developmental sequence of the female was as following: fertilization-ovulation-hatching-parturition. Right before parturition, the total length (TL) of the embryo was about 63.0 mm. When TL of maternal body was 20.0 cm, the mean numbers of the embryo were 18. The numbers of the embryo were positively related to the maternal body size.