The author sampled terrestrial mollusks in Yoyogi Park, which is a typical urban park in Tokyo, Japan. In total, 177 individuals were sampled, representing 19 species from 12 families. Thirteen species were native to the area and six were introduced species which probably spread with plants and soil along human trade routes. From the sampled mollusks, immature stages of the trematode family Brachylaimidae and parasitic nematodes Angiostoma sp., Phasmarhabditis sp. and Mermithidae were collected. The three nematodes were reported for the first time among terrestrial mollusks in Japan.