Inspired by nature, flapping-type tidal power generators have been proposed since the early 21th century. The improvement of power generation ability is one of key issues in commercializing the flapping-type generators. According to the researches of flapping-type propulsion, fluid-dynamic characteristics have been improved by morphologies such as the corrugation of scallops or the chamber of insect wings. In this study, we explore the effect of the corrugation and chamber, by mimicking a scallop, on the power generation ability. Two dimensional Navier-Stokes simulation is utilized for the numerical analysis of the morphological effects. From this analysis, we find that the morphological effects are also considerable in the flapping-type power generators, and suggest an optimal morphology in terms of the corrugation and chamber.