A substrate debonding apparatus configured to separate a support substrate attached to a first surface of a device substrate by an adhesive layer, the substrate debonding apparatus including a substrate chuck configured to support a second surface of the device substrate, the second surface being opposite to the first surface of the device substrate; a light irradiator configured to irradiate light to an inside of the adhesive layer; and a mask between the substrate chuck and the light irradiator, the mask including an opening through which an upper portion of the support substrate is exposed, and a first cooling passage or a second cooling passage, the first cooling passage being configured to provide a path in which a coolant is flowable, the second cooling passage being configured to provide a path in which air is flowable and to provide part of the air to a central portion of the opening.