A reference voltage circuit includes: a depletion type MOS transistor and an enhancement type MOS transistor connected in series, and having gates thereof connected in common, the enhancement type MOS transistor providing a reference voltage from a drain thereof, the depletion type MOS transistor including at least a first depletion type MOS transistor and a second depletion type MOS transistor connected in series; and a capacitor having one end connected to a drain of the first depletion type MOS transistor, and the other end connected to a source of the first depletion type MOS transistor.