An ionizer includes a discharge needle, a discharge needle holder holding the discharge needle, and a carrying air jet mechanism jetting out ion-carrying air toward a charge cancellation target. The carrying air jet mechanism is disposed at a position adjacent to the discharge needle holder, and it includes a drive nozzle having a drive air jet port, and a diffuser disposed in front of the drive nozzle with an ambient air suction gap interposed therebetween. A carrying air flow hole is formed inside the diffuser to be coaxial with the drive air jet port, and a carrying air jet port from which the carrying air is jetted out is formed at a fore end of the carrying air flow hole.