Chromoblastomycosis is a chronic fungal infection of the cutaneous and subcutaneous tissue resulting from implantation of certain dematiaceous fungi through the skin. The genus Fonsecaea is a major dematiaceous fungus and accounts for 90% of chromoblastomycosis. The genus Fonsecaea has been reclassified using analysis of rDNA internal transcribed spacer (ITS) region sequence; Fonsecaea (F.) pedrosoi, F. monophora, and others. In Korea, F. monophora chromoblastomycosis is very uncommon and just 4 cases have been reported. F. monophora infection was confirmed using rDNA ITS sequence analysis. Additionally characteristic sclerotic cells on both KOH preparation and histopathologiy can be helpful in making a diagnosis. A 65-year-old immunocompetent male presented with a walnut-sized, scaly erythematous plaque on left forearm for 1 year. KOH preparation showed brown sclerotic bodies and fungal culture showed dark black, velvety colonies. Long, septate hyphae with numerous conidia were observed on lactophenol cotton blue staining. Histopathology demonstrated brownish sclerotic bodies and suppurative granulomatous infiltration in the dermis. Also, sequencing analysis of the ITS region of rDNA in GenBank identified F. monophora. The lesion was successfully controlled by oral itraconazole (100mg bid for 2 months). We report a case of F. monophora chromoblastomycosis which is very rare in Korea, identified with gene sequencing analysis.