A semiconductor device includes first and second memory circuits that are disposed in different power source blocks and operate in synchronization with a clock, first and second delay circuits that are connected between output terminals of one memory circuits and input terminals of the other memory circuits, and a determination circuit that determines whether it is a situation that can cause malfunction based on an input signal and an output signal in the memory circuits and outputs a determination result as an error detection signal. To the first and second memory circuits, different initial values are given, and it is monitored whether a signal is sent and received between the memory circuits in a toggle state or not. Thus, occurrence of a situation that can cause malfunction can be simply and quickly detected.