This is to evaluate the ascending capacity of migratory fish in the pool and weir type fishways. Ascending environment of the migratory fish in rivers is analyzed through eco-hydraulic experiments using sweetfish, Plecoglossus altivelis, trout, Oncorhnchus mykiss, and surveying the fall height of existing pool and weir type fishways. When the fall height is less than 16.0cm, the ascending capacity of sweetfish in the pool and weir type fishways is greater than trout. On the other hand when the fall height is over 20.0 cm, the ascending capacity of trout is greater than sweetfish. A sweetfish may prefer to jump for upward moving than trout. And its endurance after upward jumping over wear is greater than that of sweetfish. Because of high fall height of existing pool and weir type fishways the migratory environment in rivers is so poor. When the pool and weir type fishways are designed and constructed in river the fall height of weir must be considered for the variety of migratory fish living in river and the fall height of weir less than 20.0cm is suggested.