A signal from a crystal resonator or an external clock signal are input from terminals xta1 or exta1, and the signal from the crystal resonator or external clock signal are selected by mode terminal mod8 and input to an oscillator OSC. An input clock signal ckl1 is frequency-divided to desired values by a divider DIV1. A divided clock signal clk2 is input as the reference clock of a phase-locked loop PLL1 or delay-locked loop DLL1, and a clock signal output by a circuit selected by a selector SEL3 passes via a divider DIV2 to be distributed to an LSI. The phase-locked loop PLL1 has a clock settling time of at least 40 clock periods, whereas the clock settling time of the delay-locked loop DLL1 is 2-3 periods.