Provided is an ion beam device provided with a gas electric field ionization ion source which can prevent an emitter tip from vibrating in a non-contact manner. The gas electric field ionization ion source is comprised of an emitter tip (21) for generating ions; an emitter base mount (64) for supporting the emitter tip; an ionizing chamber which has an extraction electrode (24) opposed to the emitter tip and which is configured so as to surround the emitter tip (21); and a gas supply tube (25) for supplying gas to the vicinity of the emitter tip. The emitter base mount and a vacuum container magnetically interact with each other.