A storage controlling apparatus controlling an access, for example, from a host to a physical device has a determining means determining whether or not a basic mode predetermined among two or more modes agrees with a mode set in a mode setting sequence run when the apparatus is reset or when data is transferred between modules, and a notifying means determining that transfer mode abnormality occurs when the determining means determines that the two modes do not agree with each other and sending an error notice. Whereby, a data transfer status in a mode differing from the basic mode can be detected as transfer mode abnormality, and the transfer mode abnormality can be solved.