A charge compensation device according to this invention is for suppressing charging of a wafer when the wafer is irradiated with a beam from a beam generation source unit. The charge compensation device comprises at least one first arc chamber having at least one first extraction hole and a second arc chamber having at least one second extraction hole faced on the reciprocal swinging beam of the predetermined scan range. A first arc voltage is applied to the first arc chamber to generate first plasma in the first arc chamber. The generated first plasma is extracted from the first arc chamber and introduced into the second arc chamber. Second plasma is produced in the second arc chamber, and second extracted plasma from the second arc chamber forms a plasma bridge between the second extraction hole and the reciprocal swinging beam.