A processing apparatus includes an openable/closable lid disposed on a process container, and an opening/closing mechanism configured to open/close the lid. The opening/closing mechanism includes a hinge structure swingably coupling the lid to one end of the process container, and a drive structure configured to swing the lid. The hinge structure includes a main shaft used as a rotation axis when the lid is swung by the drive structure, and an adjusting shaft located on a distal end side relative to the main shaft, for adjusting an angle of the lid.