Mammary-type myofibroblastoma is a very rare, benign mesenchymal tumor consisting of spindle-shaped cells along with thick hyalinized collagen bundles and an intralesional fat component; its histopathological features are identical to those of myofibroblastomas of the breast. It usually occurs along the embryonic milk-line; however, unusual cases occurring outside of the embryonic milk-line have also been reported. Although this tumor always shows clinically benign behavior, its variable histological composition can easily be confused with many other fibrous and lipomatous neoplasms. Unfortunately, its radiological findings are extremely rarely described in the literature. Here, we present a rare case of mammary-type myofibroblastoma in a 38-year-old woman who presented with a well-circumscribed solitary mass in the buttock, and discuss various radiologic imaging findings, such as plain radiography, ultrasonography, and magnetic resonance imaging results.