Inflammatory myofibroblastic tumor (IMT) is an uncommon soft tissue tumor mimicking malignancy, which can be found in any part of the body. However, IMT involving the prostate is extremely rare. Previous reports on prostatic IMTs mainly focused on the pathological and immunohistochemical findings of the tumor and they lacked radiological findings. This report presents a case of prostatic IMT in a 60-year-old man who presented with voiding difficulty and elevated prostate-specific antigen (PSA) level. On magnetic resonance imaging, a hypointense mass was observed on T2-weighted images with broad and extensive extracapsular extension, showing diffusion restriction, early well enhancement and delayed mild washout, which could mimic prostate cancer. On needle biopsy of the prostate mass, cancer cells were not detected; and a benign tumor was suspected with a normalized PSA level. Finally, prostatectomy was performed to rule out prostate cancer; and prostatic IMT was confirmed on histopathologic examination.