An apparatus for treating the substrate includes a process chamber having a first body and a second body which are combined with each other to have a treating space in which a substrate is treated, and a friction prevention member placed on a contact surface between the first body and the second body. The friction prevention member may have a groove formed at a surface corresponding to the contact surface. An adhesive for adhering the friction prevention member to the first body or adhering the friction prevention member to the second body may be provided in the groove. The groove may form an open-end pattern in which a first end of the open-end pattern is adjacent to a second end of the open-end pattern.