The present invention relates to a showerhead that supplies a source gas and a supporting gas for depositing a film into a processing vessel of a film deposition apparatus. The showerhead includes a body which is provided with a gas jetting surface (8). In the showerhead body, there are defined a first diffusion chamber (60) that receives the source gas and diffuses the same, and a second diffusion chamber (62) that receives the supporting gas and diffuses the same. The gas jetting surface has source-gas jetting orifices (10A) that are in communication with the first diffusion chamber, and first supporting-gas jetting orifices (10B) that are in communication with the second diffusion chamber. Each of the first supporting-gas jetting orifices (10B) are formed into a ring shape that adjacently surrounds a corresponding one of the source-gas jetting orifices (10A).