A semiconductor integrated circuit able to operate by different power supply voltages resulting from fluctuations in production, provided with a process monitor circuit for obtaining a grasp of a delay characteristic corresponding to the conditions of a production process, a memory circuit for storing data concerning an extent of process variation acquired by the process monitor circuit, and a power supply voltage control circuit for adaptively controlling the power supply voltage in accordance with the extent of process variation acquired by the process monitor circuit and stored in the memory circuit, and a test method for guaranteeing the operation of the semiconductor integrated circuit.