Floral morphology of insect-pollinated flowers should be subject to stabilizing selection, because it directly affects pollinator attraction and thus reproductive success. Therefore, variation in floral morphology in the field provides a rare opportunity to study diversification of plants through natural selection. In the family Asteraceae, the outermost florets are considered as attractors of pollinators. Aster hispidus var. tubulosus (Asteraceae) shows extreme variation in floral morphology, from ligulate to long tubular ray florets in the outermost wheel. We investigated whether morphology of outermost florets affects pollinator attraction in the field population of this species. We found the ligulate ray florets have an advantage in attracting pollinators over the long tubular ray florets. This result seemed to contradict the fact that this species has continuous variation within a population. The study population was subdivided into small patches alongside an armlet, which we found differed in the frequency of floral types. Based on this finding, we will discuss possible maintenance mechanism of continuous floral variation of this species despite the directional selection favoring ligurate ray florets.