A lithographic projection apparatus includes a liquid confinement structure extending along at least a part of a boundary of a space between a projection system and a substrate table. The liquid confinement structure is positioned adjacent a final surface of the projection system and includes a first inlet configured to supply a liquid, through which a patterned beam is to be projected, to the space, and a second inlet configured to supply gas and formed in a face of the structure. The face is arranged to oppose a surface of the substrate and the second inlet is located radially outward, with respect to an optical axis of the projection system, of the space and has a porous member to evenly distribute gas flow over an area of the second inlet.