The present invention is relating to an ion generator and an ionizer, in which the ion generator can obtain stable ion generation even if the electrode and the power supply slightly change, satisfies voltage and frequency conditions for realizing an ozone concentration less than 50 ppb as an allowable concentration. The ion generator of the present invention is characterized as a fan-type ion generator including a dielectric body, a discharge electrode having fine protrusions arranged on the surface of this dielectric body, and an induction electrode arranged on the back surface of the dielectric body, comprising: an ion element in which by applying a sinusoidal AC high voltage to the discharge electrode, a potential difference from the induction electrode is generated, plasma is formed on the surface of the dielectric body, and positive ions, negative ions, and ozone are produced according to air ionization; and a fan which generates an airflow with respect to the discharge electrode, wherein the peak-to-peak voltage is not less than 3.5 kV and not more than 7 kV, the frequency f, and the relationship between the voltage V and the frequency f satisfies a specific parameter. And, the ionizer of the present invention is characterized that ionization is performed by using the above mentioned fan-type ion generator.