PROBLEM TO BE SOLVED: To improve a design without a gap between a grill and a ceiling even when an attaching metal fitting is fastened too much due to variation in execution variation or the like.SOLUTION: A configuration that a flange 2 is provided with a radial rib 18 or a circumferential rib 19, the radial rib 18 and the circumferential rib 19 are made lower than the height of an outer peripheral wall 20, and such a structure forms a gap between the radial rib 18 and the circumferential rib 19 and a ceiling 100. Thus, the outer peripheral wall 20 of the flange 2 comes in contact with the ceiling 100, and even when fastening of an attaching metal fitting is increased, it is absorbed by the gap of the radial rib 18 and the circumferential rib 19 and the ceiling 100, and the outer peripheral wall 20 of the flange 2 surely comes in contact with the ceiling. Thus, an ion generator capable of improving a design without a gap between a grill 17 and the ceiling 100 even when the attaching metal fitting 7 is fastened too much due to variation in execution or the like.
