A substrate processing apparatus includes a chamber and units disposed above or on the chamber, at least one unit including a first groove. The substrate processing apparatus includes a lifting mechanism including at least one second groove, the lifting mechanism being configured to raise and lower each of the units. The units are configured to be raised and lowered in a state of being secured to the lifting mechanism, upon occurrence of a condition in which a fixing member is inserted into the first groove of the at least one unit and the second groove of the lifting mechanism.