A resonant circuit includes a substrate; a MEMS resonator including a fixed electrode and a movable electrode formed above the substrate and having a first terminal and a second terminal, the movable electrode having a movable portion opposing at least a part of the fixed electrode; and a voltage applying unit applying a bias voltage to the MEMS resonator, the voltage applying unit including a voltage divider circuit that includes a compensation resistance formed of a same layer as that of the movable portion to allow a resistance value to be changed by a thickness of the layer and a reference resistance formed of a layer different from that of the movable portion and connected to the compensation resistance to output a junction potential between the compensation resistance and the reference resistance to at least one of the first and the second terminals of the MEMS resonator.