A semiconductor integrated circuit includes a first circuit part that is designed under a first corner condition with respect to a process variation, a second circuit part that is designed under a second corner condition narrower than the first condition, and a control part that changes an operating voltage supplied to the first circuit part and the second circuit part according to a delay amount of the first circuit part, and starts the second circuit part when a delay characteristic caused by a change in the operating voltage conforms to a delay characteristic under the second corner condition.