A RAM mounted so as to mix with logic circuits has a plurality of memory mats and one control circuit provided for the plurality of memory mats. Arithmetic circuits for respectively performing +1 or −1 arithmetic operation are respectively provided so as to correspond to the respective memory mats and are electrically connected in cascade form. An input terminal of the initial-stage arithmetic circuit is supplied with address-setting fixed address signals. Input signals supplied to the next and subsequent arithmetic circuits or signals outputted therefrom are defined as own-assigned address signals (those assigned to the corresponding memory mats). A comparator provided in association with each arithmetic circuit referred to above makes comparisons for coincidence between the address signals and address signals input upon memory access. The corresponding memory mat is selected based on the resultant coincidence signal.