embodiment of the present invention the sense amp 300 comprises a differential amp 311 a p channel type mos transistor 312 n channel type mos transistors 313 and 314 and inverters 315 and 316 the transistor 312 has a gate a drain connected to the gate and a source connected to a high potential power supply the first transistor 313 is connected between the drain of the transistor 312 and the bit line 106 the second transistor 314 is connected between the high potential power supply and the bit line 106 the first and second transistors 313 and 314 have smaller gate capacities than the transistor 312 the second transistor 314 has a larger transistor size i e current supply capacity than the first transistor 313 the first inverter 315 has an input terminal connected to the bit line 106 and an output terminal connected to the gate of the first transistor 313 the second inverter 316 has an input terminal connected to the bit line 106 and an output terminal connected to the gate of the second transistor 314 the threshold vtp 2 of the p channel transistor for the second inverter 316 is lower than the threshold vtp 1 of the.