The ionizer of the present invention comprises a chamber which has an ionization part that ionizes a portion of an ion carrier gas that is supplied to the interior of this chamber, and a blowing part which feeds the ion carrier gas toward a charged body. The ionization part is constructed from an ionization source which is contained in the chamber, and a control device which is connected with this ionization source via a high-voltage cable. Either the generating part of a soft X-ray generating device, the generating part of a low-energy electron beam generating device or the generating part of an ultraviolet radiation generating device is used as the ionization source. The control device, the connecting part between the control device and the high-voltage cable and the connecting part between the ionization source and the high-voltage cable are formed with an explosion-proof structure.