A deposition apparatus includes a plasma gun including a hollow cathode which generates a plasma beam into a vacuum chamber including an exhaust system and one or more intermediate electrodes to provide a potential gradient for the plasma beam, a focusing coil which is provided to surround the outer surface of a tube portion of the vacuum chamber located coaxially with the exit portion for outputting a plasma beam from the plasma gun and draws the plasma beam into the vacuum chamber through the tube portion, and a reflected electron feedback electrode which is placed inside the tube portion coaxially with the exit portion of the plasma gun and has a positive polarity.