To circulate positive ions generated in a positive ion generation section toward a negative ion generation section.

An ion generator 10 includes a positive ion generation section 13 having a discharge electrode 16 formed on the surface of a first dielectric 15, and an electrode disposed to face the discharge electrode 16 with the first dielectric interposed therebetween, and a negative ion generation section 14 for generating negative ions and electrons for changing positive ions to neutral atoms. The discharge electrode 16 includes a conductive part 18 to which a positive voltage is applied, and a discharge part 17 of a sharp shape connected electrically with the conductive part 18 and generating positive ions. The discharge part 17 is provided at such a position that the conductive part 18 is not interposed between the negative ion generation section 14 and the discharge part 17.