Feeding habits of Acentrogobius pellidebilis collected from in an eelgrass(Zostera marina) bed from January to December 2006 were studied. A. pellidebilis ranged form 1.6 to 6.9 cm in standard length were determined. A. pellidebilis was a carnivore which consumed mainly copepods, polychaetes, and amphipods. Its diets included small quantities of isopods, seaweeds, nematods, and gastropods. It showed ontogenetic changes in feeding habits. Smaller individuals (<2.0cm SL) fed mainly on copepods. While the consumption of copepods decreased with increasing fish size, the consumption of polychaetes and amphipods were increased. Dietary breadth index was varied with fish size.