A timer circuit is provided including a self-holding circuit that includes a reset delay circuit for delaying an input pulse by a prescribed time. The output of the self-holding circuit is caused to fall by the rising edge of the input pulse and to rise by the falling edge of the input pulse or the rising edge of a pulse fed back through the reset delay circuit whichever occurs last. Since the pulse duration can be stretched up to a length equal to the reset delay time by the action of the self-holding circuit, the possibility of the input pulse being split through a pulse stretching circuit is eliminated.