Provided is a processing container formed of a reaction tube and a manifold that supports the reaction tube from below, and adapted to process a substrate inside, a nozzle adapted to supply a processing gas to the substrate, and a connecting portion adapted to erect the nozzle inside the processing container. The connecting portion includes (1) a fixing portion formed of a cylindrical portion inserted into an introduction portion provided at the manifold, and a flange plate formed at an end portion of the cylindrical portion, and (2) a detachable portion formed of an elbow engaged with the flange plate, and an installation portion in which the nozzle is installed.