Unilateral multicentric cancer of the breast containing a tumor with a specific histopathological type is comparatively rare. We, herein, report a case of an unilateral multicentric cancer of the breast containing two separate tumors diagnosed as a papillo-tubular carcinoma and an invasive lobular carcinoma. In addition to the difference in histological type, these two tumors also had different patterns of expression of hormonal receptors reflecting the cellular aggressiveness. Therfore, these tumors may be formed through multicentric tumorigenesis.