The male breast cancer is very less common as compared with the female breast cancer. We report a case of 64-year-old man who presented with the history of lower urinary tract symptoms. The digital rectal examination revealed hard and nodular prostate, and serum prostate-specific antigen level was 23.4 ng/mL. Ga-labeled prostate-specific membrane antigen PET/CT revealed prostate-specific membrane antigen-expressing lesions in the prostate, axillary tail of the right breast, and axillary lymph nodes. Histology from prostate revealed prostate carcinoma, whereas fine-needle aspiration from the breast revealed invasive ductal carcinoma of the breast.