A gray mold disease occurred on Cryptotaenia japonica in Korea. All the isolates of Botrytis sp. from the lesions of the diseased plants were identified to be B. cinerea based on the morphological characteristics. Conidia formed on conidiogenous cells were not in chains, hyaline to pale brown, unicellular, ellipsoidal to obovate with a single hilum at the base, entirely verruculose, and $6.3-11.3{sim}6.3-10.0{mu}m$ in size. Pathogenicity of the fungus was proved by artificial inoculation on C. japonica. This is the first record of gray mold on C. japonica caused by B. cinerea in Korea.