provided is an ion generator that has a potential sensor provided integrally inside the main body of the ion generator , and that can measure , with the potential sensor , an electric field that reaches the potential sensor from a member from which static charge is to be eliminated , without being affected by an electric field between a discharge electrode and an opposing electrode . this ion generator comprises a discharge electrode , an opposing electrode , and a main body part including these electrodes , the ion generator sending out , toward a member from which static charge is to be eliminated , air ions generated by applying a high voltage between the electrodes . a potential sensor that measures the potential of the member from which static charge is to be eliminated is provided integrally to the main body part , and a projecting electrostatic - shielding plate that projects from the main body part is provided between the potential sensor and a discharge part constituted by the discharge electrode and the opposing electrode .