The microcomputer includes the oscillation circuit which outputs an
oscillation signal and stops output of the oscillation signal when it
receives an oscillation stop signal. The microcomputer receives the
wakeup signal of a predetermined cycle at the wakeup terminal. There is
provided the clock control circuit which receives the wakeup signal and
the oscillation signal, outputs the oscillation stop signal thereby
making the oscillation circuit stop output of the oscillation signal, and
stops output of the oscillation stop signal based on the wakeup signal
thereby making the oscillation circuit restart output of the oscillation
signal.