Changes in breeding bird community and forest structure by thinning were investigated from April 1997 to August 1998 in l0㏊ (400 × 250m) of temperate mixed hardwood forest in Mt. Gariwang which is located in National Forest, Pyoungchang, Kangwon Province, Korea. Bird community was surveyed by the territory mapping method and forest structure was done by analyzing the vertical structure of foliage, distribution of diameter at breast height (DBH) of trees and tree species composition. After the thinning, tree density, number of tree species and basal area were decreased from 195ea/㏊, 18 species and 6.69㎡/㏊ into 100ea/㏊, 13 species and 3.04 ㎡/㏊, respectively. Foliage coverages in upper and mid layer were decreased, but coverage in low layer was increased. Large trees (Over 40㎝ of DBH) were decreased. Number of breeding bird species and pairs were decreased from 14 species and 23 pairs into 8 species and 12 pairs after the thinning. Number of breeding pairs of Yellow-breasted bunting Emberiza elegans incresed. There were decrease in number of species in hole & bush-nesting and canopy & bush-foraging guild. The results suggested that the thinning affect the species composition of breeding bird community and the forest structure. Changes of habitat structure might influence in breeding bird`s density, species diversity and habitat using pattern of breeding bird community.