A plasma process apparatus capable of preventing generation of plasma in an unwanted location and performing uniform plasma processing with stability is obtained. The plasma process apparatus includes a processing chamber having an internal wall surface; a microwave radiating member having one wall surface and the other wall surface that faces the internal wall surface of the processing chamber, and being disposed such that a space is formed between the other wall surface and a portion of the internal wall surface, and propagating and radiating microwaves within the processing chamber; and a reactive gas supply member, including a reactive gas supply passage having a space formed between the other wall surface of the microwave radiating member and the internal wall surface; and a microwave transmission preventing member disposed on a region, which faces the reactive gas supply passage, of the other wall surface of the microwave radiating member.