PURPOSE: To contrive to simplify the circuit constitution by constituting a power-on clear circuit using a resistor section, a capacitor section and an inverter built in the master slice system semiconductor device.

CONSTITUTION: The resistor section 3 and the capacitor section 4 are connected in series with a wire part 1 and the other end of the capacitor section 4 is grounded. Moreover, a connecting point 5 between the resistor section 3 and the capacitor section 4 is connected to an input terminal 7 of the Schmitt trigger type inverter 6 and its output terminal 8 is connected to e.g., a reset input terminal of a flip-flop. Thus, an initializing signal is outputted from an output terminal 8 of the inverter 6. An on-resistance of a P-channel MOS transistor (TR) 11 is used as the resistance section 3 and a capacitor section comprising a gate capacitance between a gate electrode of an N-channel MOS TR 12 and a semiconductor substrate is used as the capacitor section 4.