Forest fragmentation by urbanizing and developing roads and fields is common in Japan; thus, the Siberian flying squirrel (Pteromys volans) population may decrease in the future. This study examined the effects of urbanization on P. volans by clarifying their home ranges and nest arrangements. Ten flying squirrels were captured and radio-telemetrically tracked from 2005 to 2007 in Obihiro City in eastern Hokkaido (Northern Japan). Males had significantly larger 100% MCP (minimum convex polygon) areas (mean ± SD; 6.5 ± 5.1 ha) and 95% MCP areas (3.6 ± 1.3 ha) than females (1.8 ± 1.0 ha and 1.0 ± 0.5 ha, respectively). Also the core area of males (1.2 ± 1.1 ha) was larger than females (0.2 ± 0.2 ha), though this difference was not significant. Males and females used more nests located inside than outside of their core areas. Distance from the core area edge to the nest located outside the core was longer for males (78.6 ± 139.9 m) than for females (39.7 ± 39.9 m), but this difference was not significant. Siberian flying squirrels in urban forests likely show similar ecology with flying squirrels in consecutive forests; however, they might change their behavior to share resources with others because urban forests restrict nest and food resources.