In early August of 2011, following a prolonged period of cool and moist weather, several trees of boxelder maple (Acer negundo) planted in Mt. Soyo located in Dongducheon, Korea, were found to be heavily damaged by premature defoliation with zonate leaf spot symptoms. Numerous number of cone-shaped, white sporophores (conidia) were observed on lesions of the abaxial leaf surface. The morphological characteristics of conidia are of typical Cristulariella moricola, which was supported by analyzing sequences of internal transcribed spacer region of ribosomal DNA. Pathogenicity of the fungus was proved by artificial inoculation in the condition of relative humidity 100% and 18 ± 2oC. This is the first report of the occurrence of zonate leaf spot caused by infection of C. moricola on A. negundo in Korea.