Oscillator circuit uses a comparator, and controls charge-discharge of Miller capacitance between gate and drain of a MOSFET serving as an amplifier of the comparator gain unit and gate capacitance of the MOSFET, and enables comparator output to follow a high-frequency control signal that is input externally. An oscillator circuit uses a comparator CMP having differential and gain units. This oscillator circuit includes: a charge-discharge controller to control charge-discharge of Miller capacitance between gate and drain of a MOSFET and gate capacitance of the MOSFET; and an output controller to control output of the gain unit. Output controller includes: an inverter to connect to an input of the differential unit and receive a control signal input; a logic circuit to receive output of the inverter and output of the gain unit as an input; a transistor; and a capacitor to connect to input and output of the logic circuit.