The fishways at Namdae-cheon and Osib-cheon were investigated from July 1998 through October 1999. There are three types of fishways on these rivers. those are baffied fishway, fish ladder, and fish ladder with gabion. Namdae-cheon has 7 baffled fishways and 19 fish ladders, and Osib-cheon has 7 gabion fishways. On namdae-cheon, 1,775 fishes of 24 species were collected. Among these fishes, 452 fishes of 11 species were anadromous fishes occupying 46% in species and 25% in number. On Osib-cheon, 1,953 fishes of 24 species were collected. Among these fishes, 483 fishes of 5 species were anadromous fishes occupying 21% in species and 25% in number. On Namdae-cheon the species number and abundance decreased gradually upstream. The poor structure of fishways seems to have worked as an obstacle to the upstream migration of fishes in the Namdae-cheon . On Osib-cheon all the observed fish species except three-spined stickleback(Gasterosteus aculeatus aculeatus) which stay and spawn around downstream of fiver could migrate upstream. The good structure of fishways on this river is thought to have helped upstream fish migration.