Dispersal phenology are diverse among organisms. However, the evolutionary mechanisms underlying this diversity have not yet been understood well. In ant-dispersed plants, functionally relevant disperser attributes, i.e. its abundance, species composition, and species richness vary seasonally. Thus, ant-dispersed plants need to fruit when the highest dispersal success is achieved. Notable here is that the “best” period may vary among species for which the relative importance and/or the optimal state of each attribute is different, potentially leading to the evolutionary divergence in fruiting phenology. To test this idea, I focused on the difference in fruiting phenology of two ant-dispersed sedges: Carex lanceolata and C. tristachya. I surveyed the disperser ant assemblage periodically during their fruiting periods. Then I evaluated the seasonal change in the assemblage and its association with the fruiting period of both sedges. The abundance and richness of disperser increased with date, but the proportion of Formica japonica, a long-distance seed disperser, decreased. Consequently, earlier fruiting of C. lanceolata coincided with high proportion of the long-distance disperser, while later fruiting of C. tristachya with abundant and species-rich season of the disperser. This indicates that the relative importance and/or optimal state of the attributes differ among sedge species.