Vincetoxicum pycnostelma (Apocynaceae) is a perennial species growing in grassland in Japan, Korea, China, and western part of Amur. For the last several decades, habitats of the species have been rapidly decreasing due to succession of grassland. This species is ranked as a “Near Threatened” species in Japan (Ministry of the Environment, Japan, 2007). For conservation of the species, to clarify its effective pollinator is indispensable, but such information is lacking. We observed visitor to the flowers from 5:30 to 9:00 and from 17:30 to 21:30, and collected them at the populations in the embankments of Kidzu River, Kyoto, Japan from June to August in 2011. Fruit set was investigated and 124 flowers were sampled. Pollinaria attached to the insects and pollinaria on the stigmatic chambers were investigated in a laboratory. Twenty seven species of nine families of three orders visited flowers, and among them 15 species of six families of one order contributed pollination. Small moths with proboscis lengths from 0.9 to 4.5 mm mainly carried pollinaria. Most of pollinators are common in the region. The percentage of flowers in which pollinaria were removed and the percentage of flowers inserted pollinaria were much higher than fruit set percentage. The reasons may be due to self-incompatibility or selective abortion.