Apparatus and method for forming a deposited film by a means of plasma CVD

A film-forming apparatus comprising a substantially enclosed vacuum chamber whose inside being capable of being evacuated, a power application electrode having a desired thickness for introducing a discharging power into said vacuum chamber, a raw material gas introduction potion through which a raw material gas is introduced into said vacuum chamber, and an exhaustion portion through which said vacuum chamber is exhausted, said power application electrode being arranged so as to oppose a substrate positioned in said vacuum chamber, wherein a discharging power is introduced through said power application electrode to generate a plasma in a discharge space between said power application electrode and said substrate to decompose a raw material gas introduced through said raw material gas introduction portion whereby causing deposition of a film on said substrate, characterized in that at least said raw material gas introduction portion or said exhaustion portion is provided with an opening adjusting member having a desired thickness for intercepting said plasma, and said power application electrode and said opening adjusting member are arranged to satisfy an equation a or c≧b, with a being a shortest distance between said power application electrode and said opening adjusting member provided at said raw material gas introduction portion, c being a shortest distance between said power application electrode and said opening adjusting member provided at said exhaustion portion, and b being an average distance between said substrate and a horizontal plane face of said power application electrode which is opposed to a face of said substrate.