There is provided a semiconductor device of which the circuit scale does not significantly increase even with an ECC function. A microcomputer having an internal flash memory inserts one weight in a sense amplifier activation signal only when an error detection signal is on the H level at a given time in a read cycle or when the error detection signal which was on the H level in a previous read cycle has shifted to the L level in a current read cycle. This allows the retrieval of output data signals after waiting till the output data signals through error correction are determined only when an error is contained in the output data signals.