PURPOSE: To prevent outputting erroneous data even though a memory cell makes an erroneous selection by detecting an address change and controlling the output level of a sense amplifier through a P channel transistor(TR).

CONSTITUTION: A sense amplifier consists of P channel TR1 and 2, which configure a current mirror circuit, N channel TR3 and 4 which are serially connected to the N channel TRs and a complementary inverter 5 and the output of the sense amplifier is outputted through an output buffer 19. When an address detecting circuit 18 detects an address change, a P channel TR16 is turned off, the TR2 is turned off through a P channel TR17, the output level of the sense amplifier is reduced and an erroneous data output is prevented during an erroneous selection of the memory cell.