PURPOSE: To facilitate the detection of defect product whose operation area depending on an internal generation voltage is narrow by connecting a data signal input terminal with an internal voltage supply line through a signal line and connecting a data input circuit with a data output circuit.

CONSTITUTION: An internal signal generation part 10 shifts switches 21, 22, 23 based on an input signal and the input address data. The switch 21 connects a data input buffer 5 with a data output buffer 3, and the switch 22 connects a signal input part 1 with the signal line 24, and the switch 23 connects the signal line 24 with the internal voltage supply line 9. A data signal inputted from the data input terminal 1 is inputted to an I/O line 7 through the data input buffer 5 and a write driver 6 to be inputted to a memory cell 15. Then, the read out data signal is supplied to a data output terminal 2 through the I/O line 7, a preamplifier 4, the data output buffer 3.