A processing apparatus includes a processing container, a manifold having an injector supporting part, the injector supporting part being disposed at a lower end of the processing container, extending along an inner wall surface in the processing container and having an insertion hole, and a gas introduction part having a gas flow passage within the gas introduction part to communicate with the insertion hole and an outside of the processing container so that a gas flows in the gas flow passage, an injector inserted and fixed into the insertion hole, the injector entirely extending in a linear manner along the wall surface and having an opening communicating with the gas flow passage at a location where the injector is inserted into the insertion hole, and a gas supplying pipe communicating with and connected to an outer end of the gas flow passage of the gas introduction part.