The inventive concept relates to a substrate treating apparatus including a process chamber having a first and a second body, a support unit supporting a substrate, a heating unit heats the substrate, a driver moves any one of the first body and the second body, an interval state detection unit that detects an interval state between a side wall of the first body and a side wall of the second body when the first and the second body are placed in a process location, and a controller that controls the driver and the interval state detection unit, wherein the interval state detection unit includes a pressure provision line that provides a positive pressure or a negative pressure between the side wall of the first body and the side wall of the second body, and a pressure measurement member that measures a change in a pressure of the pressure provision line.