Background and Objective: Stomach contents of Pseudopleuronectes yokohamae collected from mid-Western coast of Korea were analysed to determine dietary composition as a function of fish life stage, water temperature and time. This study was to provide needed data on feeding behavior to aid in conservation and management for this ecologically and economically important species of fish. Materials and Methods: Prey items were identified to the lowest possible taxa with a dissecting microscope. Distance-based linear modelling (DISTLM) using total length, maturity, sampling month, water temperature and sex as predictors was used to assess diet composition. Logistic regression on stomach fullness (0: empty, 1: with content) using the same predictors as above was used to assess feeding intensity. Results: Fish Total Length (TL) ranged between 8.6 and 26.8 cm. Polychaetes dominated the diet of both smaller and larger fishes. Ophiuroids and bivalves were secondary and more frequently consumed by larger specimens. Distance-based linear modelling showed diet composition of P. yokohamae varying significantly with maturity and Total Length (TL) but not with sampling month, water temperature, nor gender. Conclusion: Data showed P. yokohamae select for polychaetes, foraging near the substrate. Mature individuals consumed more ophiuroids than did juveniles, indicating intra-specific competition avoidance during feeding for this species.