A gate drive circuit includes: a modulation circuit that generates a first modulated signal and a second modulated signal; an isolator including a first electromagnetic resonance coupler that isolatedly transmits the first modulated signal, and a second electromagnetic resonance coupler that isolatedly transmits the second modulated signal; a first rectifier circuit that generates a first signal by rectifying the first modulated signal; a second rectifier circuit that generates a second signal by rectifying at least a part of the second modulated signal; a third rectifier circuit that generates charging voltage by rectifying a second radio-frequency wave; a capacitor that charges a charge in accordance with the charging voltage; and an output circuit which selects whether or not to supply the charge charged in the capacitor to a gate terminal of the semiconductor switch, in accordance with at least one of the first signal and the second signal.