Abstract: An apparatus and a method for plasma surface treatment which treats a surface of a treatment portion of an electrically conductive object using ions from plasma are disclosed. The apparatus includes a connector electrically connected to the treatment portion for applying negative voltage pulses to the treatment portion; a pulse voltage generating unit electrically connected to the connector; and magnetic cores disposed at the boundary of the treatment portion for preventing electric current caused by the negative voltage pulses applied to the treatment portion from flowing across the boundary of the treatment portion is provided. The apparatus and method for plasma surface treatment can confine the treatment portion by using negative high voltage pulses and magnetic cores. Also, the apparatus and method can apply negative high voltage pulse to the treatment portion of an electrically grounded object such as a metal sheet coil and a metal wire coil.