Breast cancer in male is rare, accounting for 1%of all breast cancers.Among male breast cancers, noninvasive carcinoma is extremely rare.We experienced a case of noninvasive carcinoma of the breast in a male.A 72-year-old male was referred to our hospital with a chief complaint of the tumor and blood secretion from the left nipple.Mammography revealed a highdensity mass.Ultrasound examination revealed low echoic mass at the E area, and it measured 1.5 cm.Core needle biopsy failed to provide a definitive diagnosis, and we performed an excisional biopsy of the tumor.The pathological diagnosis was noninvasive ductal carcinoma.He underwent a mastectomy without sentinel lymph node biopsy because the resection margin was positive.The patient received no adjuvant therapy and the patient's postoperative course was uneventful for 1 year.As there have been few reports on male noninvasive ductal carcinoma, we do not have evidence for indication of the sentinel lymph nodes and postoperative adjuvant therapy such as tamoxifen.We may confuse the treatment policy.