Provided are an apparatus and method for treating a substrate. Specifically, provided are an apparatus and method for treating a substrate through a supercritical process. The apparatus includes: a housing providing a space for performing a process; a support member disposed in the housing to support a substrate; a supply port configured to supply a process fluid to the housing; a shield member disposed between the supply port and the support member to prevent the process fluid from being directly injected to the substrate; and an exhaust port configured to discharge the process fluid from the housing.