A current/charge-voltage convert circuit having an operational amplifier and a capacitor connected between the input terminal and the output terminal of the operational amplifier, this current/charge-voltage convert circuit characterized in that it comprises a first pair of diodes connected in mutually opposing directions to this input terminal, a second pair of diodes connected in the opposite direction of this first pair of diodes to the respective other terminal of this first pair of diodes, a pair of current sources connected in mutually opposing directions to the respective other terminal of this first pair of diodes, a pair of switches connected to the respective other terminal of this first pair of diodes, and resistors connected between the respective other terminal of this second pair of diodes.