In a delay circuit for inputting square waves, fluctuations in the amount of delay brought about by noise pulses present in input signals are reduced. A switch (SW3) is controlled by an output signal (Vdo) from a Schmitt comparator, and selects either an electric current source for supplying a charging current to a capacitor (Cst) or an electric current source for supplying a discharging current. A current supply from the selected electric current source is turned on/off by controlling switches (SW1, SW2) using an input signal (Vdi). The Schmitt comparator switches the level of Vdo in accordance with a voltage of Cst. The charging current is supplied to Cst when Vdi is H level at rising edge of Vdi, and the discharging current is supplied to Cst when Vdi is L level at trailing edge of Vdi.