1. A microcomputer that executes a process in synchronization with a clock, comprising: a process switch control circuit that includes a first register, and stores clock usage information specifying which clock is to be used for execution of a next process in the first register every time processes to be executed are switched; and a clock control circuit that includes a second register, stores the clock usage information in the second register after the clock usage information has been stored in the first register, and selects and outputs a clock from a plurality of clocks in accordance with the clock usage information stored in the second register.