A microcontroller includes a data input unit that receives input data and outputs a start request signal according to the input data upon receiving the input data; an oscillator that starts according to the start request signal, to generate a clock signal; a clock signal supply control unit that outputs the start request signal supplied from the data input unit to the oscillator, and supplies the clock signal supplied from the oscillator generated after the start as a first clock signal and a second clock signal that are operation clock signals of the data input unit; and a CPU that operates the second clock signal as an operation clock, and performs processing according to the input data when the second clock signal is operated.