Abstract: A malfunction detection circuit realized by a simple circuit structure is incorporated into a semiconductor integrated circuit without increasing the scale thereof, in order to prevent loss etc. of data due to a malfunction of the semiconductor integrated circuit. Malfunctions can be prevented without relying on measuring temperature or power supply voltage which are analog values, thereby improving the reliability of the semiconductor integrated circuit. A detection-target flip-flop in a function block is synchronized to a clock, and another flip-flop is synchronized to a clock whose phase has been delayed behind or advanced ahead of the former clock. A logic operation is performed using output from both flip-flops to determine whether a latch operation has been performed at an appropriate clock pulse edge in a clock pulse train. The malfunction countermeasure is performed if the latch operation is determined to have been performed at an inappropriate clock pulse edge.