In a Hall thruster 10, an acceleration channel 12 ionizes propellant flowing into an annular discharge space 11 to generate ions, and accelerates and discharges the generated ions. A distributor 37 supplies propellant from a plurality of holes 13 arranged azimuthally, via an anode 14 penetrating to the discharge space 11 of the acceleration channel 12, to the discharge space 11 of the acceleration channel 12, an amount of the propellant varying according to positions of the plurality of holes 13, thereby generating a plurality of regions, between adjacent ones of which the mass flow rate of the propellant is different, azimuthally in the discharge space 11 of the acceleration channel 12. During that time, the distributor 37 adjusts, with respect to the mass flow rate of the propellant in the discharge space 11 of the acceleration channel 12, a differential within a range of 5 to 15% between the mass flow rate of the propellant in a region with a large mass flow rate of the propellant and the mass flow rate of the propellant in a region with a small mass flow rate of the propellant. Thus, the width of a operation parameter region with reduced discharge current oscillation of the Hall thruster 10 is expanded.