This electrical discharge device (30) comprises: a discharge stabilizing member (37) disposed, relative to a facing electrode (36), on the other side of a discharge electrode (35) sandwiched therebetween, and constituted to have the same polarity as the discharge electrode (35) and an adjustment unit (40, 41) for adjusting voltage difference V1-V2 between the voltage V1 of the discharge electrode (35) and the voltage V2 of the discharge stabilizing member (37) in such a manner as to switch between a first operation in which a streamer discharge is carried out from the discharge electrode (35) toward the facing electrode (36), and a second operation in which a glow discharge is carried out at the discharge electrode (35).
