Oscillator Circuit and Semiconductor Device

An oscillator circuit includes a capacitance element; an inverter outputting an inverted voltage at a first terminal of the capacitance element; a voltage source including a resistor and an NMOS transistor connected in series between a first high-potential power supply and a ground power supply and outputting a voltage from a node to which the resistor and the NMOS transistor are connected; a switch circuit connecting a second terminal of the capacitance element to the voltage source or the ground power supply in accordance with the voltage output from the inverter; and a constant-current source connected to a second high-potential power supply and allowing, regardless of changes in the voltage and temperature of the second high-potential power supply within certain ranges, flow of a constant current into or out of the first terminal of the capacitance element in accordance with the voltage output from the inverter.