Feeding habits of the largemouth bass Micropterus salmoides in Ono Lake, Yamaguchi Prefecture, Japan were studied based on stomach contents of 571 specimens (144-440mm in standard length) collected from January, 2005 to June, 2007. Important prey items of this fish were Hypomesus nipponensis, Macrobrachium nipponense. Odontobutis obscura, Gnathopogon caerulescens, Squalidus gracilis gracilis and Ischikauia steenackeri. H. nipponensis was the most important prey throughout the year, especially from autumn to spring. The feeding activity declined in winter and for breeding related bass during the spawning period. With growth the frequency of occurrence of I. steenackeri increased, while that of G. caerulescens and S. gracilis gracilis decreased.