A plasma accelerating apparatus and a plasma processing system, which efficiently elevate a drift velocity of a plasma beam and are simple to manufacture and simple in construction. A channel includes an outlet port opening at an end of the channel. A gas supply portion supplies a gas in the channel. A plasma generator provides ionization energy to the gas in the channel to generate a plasma beam. A plasma accelerating portion includes a plurality of grids transversely arranged spaced apart from each other by a predetermined distance in the channel for accelerating the plasma beam generated by the plasma generator to the outlet port of the channel with an electric field. The plasma accelerating apparatus and the plasma processing system elevate a drift velocity of the plasma beam more efficiently than conventional accelerating apparatuses that use an electromagnetic force induced by a magnetic field and a secondary current.