A boost voltage circuit includes a plurality of N channel type MOS transistors connected between an input terminal and an output terminal in series, wherein one electrode of each of the N channel type MOS transistors is connected to each of external terminals to which a capacitor can be connected, to generate a boost voltage. A plurality of P channel type MOS transistors are respectively connected to each of the N channel type MOS transistors in parallel. Thereby, a boost voltage circuit with improved stability is provided so that the boost voltage circuit is started without increase of consumption current.