The object is to avoid an erroneous operation during a term in which an initialization is performed when a command is input.After a power source is turned on, a low level of a power-on-reset signal PWONRSTn is output until it reaches a power-on detect level. It is inverted by an inverter IN11, and input to a NOR circuit NR 11 likewise commands 1 and 2, so that a status is set to a busy status. The busy status is kept during a term in which a initialization operation is performed until the power supply voltage reaches the power-on detect level. Further, the status is read out to the exterior by a status read out mode signal to notify a user. As a result, it prevents from being input a command by an erroneous operation of a user during the initialization operation term.