A phase shift mask having a first region and a second region in a transverse direction includes a transparent layer, a phase shift pattern disposed in the first region, a transmittance control layer pattern disposed in the second region, and a shading layer pattern disposed on the transmittance control layer pattern. The phase shift pattern has a first pattern including a transparent material and a second pattern including metal. The phase shift mask may prevent haze effects through a cleaning process using an alkaline cleaning solution.