Disclosed is a charge neutralizing device which is capable of being applied to a substrate 13 having a large area and in which electrons having low energy of 5 eV or less, and preferably 2 eV, are supplied so that charge due to ion implantation and damage by the electrons are avoided with respect to a cusp device. The charge neutralizing device includes a microwave generating unit, a plasma generating unit that generates electron plasma using a microwave generated from the microwave generating unit, and a contact unit that brings the electron plasma generated from the plasma generating unit into contact with a beam plasma region including an ion beam.