A semiconductor device addresses to a problem in which a current consumption variation rate increases during BIST execution causing resonance noise generation in a power supply line. The semiconductor device includes a self-diagnosis control circuit, a scan target circuit including a combinational circuit and a scan flip-flop, and an electrically rewritable non-volatile memory. A scan chain is configured by coupling a plurality of the scan flip-flops. In accordance with parameters stored in the non-volatile memory, the self-diagnosis control circuit can change a length of at least one of a scan-in period, a scan-out period and a capture period, and can also change a scan start timing.