Intramuscular myxoma is a relatively rare benign tumor. However, difficulty in differentiating this lesion from malignant tumor is sometimes encountered. On MRI, this lesion shows characteristic findings of a clear border, lower intensity than skeletal muscle on T1-weighted images and higher intensity than fat on T2-weighted images, as wellas a homogeneous internal structure. In our present case, an intramuscular myxoma in the thigh showed the same findings. MRI is useful modality for diagnosing of this tumor.