A semiconductor device able to improve data retaining characteristics and decrease power consumption, further able to realize more unrestricted system without increasing excessive circuits, and having the following: an ALPG receiving a start signal and a mode selection signal to generate commands and addresses with respect to a DRAM circuit with the predetermined patterns in accordance with modes, and outputting an ending signal when ending a pattern generating processing in each of modes; an ECC circuit receiving a start signal and a mode selection signal indicating a parity generation mode to generate a parity based on data read from the DRAM circuit, receiving the start signal and a mode selection signal indicating an error correction mode to perform an error correction with respect to data read from the DRAM circuit based on the parity generated in the parity generation mode and outputting data after correcting; and an interface circuit.