A case of extraskeletal myxoid chondrosarcoma is reported. A 42-year-old man presented to our clinic for local excision of tumor arising in the right brachial plexus. His tumor was diagnosed as a neurinoma by CT and MRI findings. We performed excision of the tumor but adhesion to the brachial plexus made this very difficult, and it was not possible to excise all of the tumor perfectly. Histopathological examination showed that the tumor was composed of many nodules in which tumor cells were arranged in cords or strands in the abundant myxoid matrix. Histological diagnosis was an extraskeletal myxoid chondrosarcoma. The CT and MRI findings of extraskeletal myxoid chondrosarcoma are the same as neurinoma making it difficult to preoperatively diagnose extraskeletal myxoid chondrosarcoma.