A mask manufacturing apparatus includes a laser irradiator, a stage, a frame, and a heat spreader sheet. The laser irradiator divides a laser beam into a plurality of sub-laser beams and irradiates the sub-laser beams to a shadow mask material which is placed over a stage. The frame is disposed over the stage to support the shadow mask material. The heat spreader sheet makes contact with the shadow mask material, absorbs heat generated from the shadow mask material, and dissipates the heat to surroundings of the shadow mask material. Accordingly, the shadow mask material is protected from overheating.