This study presents data on spawning season, length-weight and length-length relationships, and seasonal condition factors of Chaenogobius gulosus (Sauvage, 1882) inhabiting rocky subtidal habitat in the south-eastern Korea. Monthly changes in the gonadosomatic index (GSI) indicated that the spawning period was from December to April. Values of the exponent b, estimated by nonlinear least squares from weight and length data, ranged from 2.860 for mature group to 3.184 for immature fishes, but it was similar between spawning and non-spawning seasons, and between female and male fishes. All relationships between total and standard length were linear (r²> 0.947). The condition factors were significantly higher during the spawning season than during the non-spawning season, but those were not significant between immature and mature groups, and between female and male fishes. The results from this study can contribute to increasing our knowledge on biology of C. gulosus, and are useful data for conservation and management of this species.