Population synchrony may be generated by dispersal, Moran effects, and trophic interaction. However, the dominant processes are hardly identified in the in the field because all three agents may produce nearly identical signatures. This study separately analyzed the effects of the three agents in the gray-sided vole populations. Dispersal was assessed by genetic relatedness among populations, Moran effects were measured by density independent elements in population dynamics, and trophic interaction was inferred from density dependence structure in population dynamics. Population synchrony was represented as a function of geographic distance. Correlation of density independent and relatedness also decayed with geographic distance, whereas density dependence structure did not show any relationship with geographic distance. A multiple regression analyses using population synchrony as a response variable and using density independent synchrony, relatedness, and density dependence structure as explanatory variables showed that all three variables significantly contributed to explaining the variation of population synchrony. Among the three variables, density-independent synchrony was most influential followed by relatedness and density dependence structure. The relative importance of the three factors in the generation of population synchrony will be discussed.