A film deposition apparatus includes a process chamber, and a turntable in the process chamber to receive a substrate. An exhaust port is provided outside the turntable to evacuate the process chamber. An exhaust box is provided in a space between a ceiling surface of the process chamber and the surface of the turntable so as to surround a certain region along the circumferential direction and a radial direction by side walls so as to include a region upstream of the exhaust port in a rotational direction of the turntable. A gas supply unit to supply a gas into the exhaust box is provided. The exhaust box includes an outflow port in a side wall closest to the exhaust port such that a conductance of a gas flowing from the exhaust box increases with increasing distance from the exhaust port.