A handheld punch cutting device for cutting rounded corners in flat roll roofing material. The cutting device comprises a pair of handles terminating in flat plate-like reciprocating jaws, the upper jaw having an arcuate compression cutting blade and the lower jaw having a flat compression cutting plate with raised, spaced guides for locating a corner of roofing material centrally beneath the cutting blade. The height of the guides is less than the height of the blade, and the blade directly and continuously contacts a substantially flat cutting surface on the compression plate in order to complete a cut.