A paint mask for shielding a surface to be masked from paint being applied to an adjacent or nearby surface is described. The paint mask is formed of an elastic, substantially gas-impermeable material and has a suction cup surrounded by a flange. Together, the suction cup and flange are sized and shaped to cover the surface to be masked. In the side of the flange which contacts the surface to be masked, there are channels which communicate with the interior of the suction cup, such that when the paint mask is placed on the surface to be masked, an enclosed space is defined by the suction cup, the channels and the surface to be masked. Pressing down on the outside of the suction cup causes a portion of the air inside the enclosed space to escape. When the suction cup is released, a partial vacuum forms in the enclosed space which fixes the paint mask to the surface to be masked.