There is provided a substrate processing apparatus of performing a process by supplying a processing gas on a substrate while rotating the substrate mounted on a rotary table in a vacuum container, which includes: a container main body used as a part including a bottom portion of the vacuum container; a cover part configured to be detachably installed with respect to the container main body to open and close the container main body, the cover part being used as a part including a ceiling portion of the vacuum container; a pillar installed in one of the cover part and the container main body such that the pillar penetrates through a central portion of the rotary table when the cover part is installed on the container main body, and configured to support the cover part with respect to the container main body when the inside of the vacuum container is vacuum-exhausted.