a discharge plasma generating method includes opposing a discharge electrode having a substantially plane discharge portion to a substrate to be processed in a vacuum reaction vessel such that the discharge electrode and the substrate are substantially parallel to each other , evacuating the vacuum reaction vessel and supplying a process gas to a space between the discharge electrode and the substrate , and applying hf power to the discharge electrode such that an envelope representing the spatial distribution of a hf voltage φ on the discharge electrode in a split second changes in accordance with a function including time as a parameter , thereby generating a discharge plasma of the process gas between the discharge electrode and the substrate , with substantially no standing wave of the hf voltage φ generated on the discharge electrode .