This study was conducted to analyze the breeding bird community by using guild concept in Mt. Baekwoon Research Forest of Seoul National University. Bird Community was studied by line transect method during the breeding seasons of birds in 1982 and its results were compared and analyzed with the Park et al. Work in 1993. Guilds were characterized by nesting and foraging sites as follows: nesting guild - (H) hole, (C) canopy, (B) bush, (E) edge; and foraging guild - (o) outside, (c) canopy, (b) bush. Bush-nesting guilds such as Tricolor Flycatcher (Ficedula zanthopygia), Blue-and-White Flycatcher (Cyanoptila cyanomelana), Stonechat (Saxicola torquata), Bush Warbler (cettia diphone) and Skylark (Alauda arvensis) had disappeared after ten years. Outside-foraging guilds such as Common Buzzard (Buteo buteo), sparrow Hawk (Accipiter nisus) and Carrion Crow (Corvus corone) also were not observed. There was a sharp decrease of species richness of bush-nesting guild, canopy-foraging guild and bush-foraging guild compared to ten years ago. These decreases indicate that forest environment of this area has been changed for the ten years, and guild concept in this study can be used usefully to elucidate the change of bird community according to the change in forest environment.