Amazing petal diversity in angiosperm flowers has been thought to evolve in relation to diversified visual-attraction function to pollinator. Nevertheless, it is difficult to explain the whole diversity only with this function. Petals are known to have functions of landing site for pollinators as well. However, it is not easy to examine the importance of landing-site function separately, this is because most petals have both visual attraction and landing-site functions. In this study, we investigated landing-site function of petals in scent-attracted fungus gnat-pollinated Mitella pauciflora flowers, which have inconspicuous and pinnately-branched petals. Fungus-gnat pollinated flowers are ideal subject to test landing site function of petals, because their petals are expected to less involved in visual attraction function than those of bee- or syrphid fly-pollinated flowers. Here, we tested the hypothesis by conducting a petal removal experiment which examined the effects of petals on approaches, landings, visit durations and successive probes per visit by pollinators and mating success in naturally-pollinated M. pauciflora flowers. According to our experimental results, we discuss landing-site function of petals in flowering plants.