A mask and a manufacturing method thereof are provided. A transparent substrate having three regions is provided first. A non-transmitting layer is formed in a first region of the transparent substrate. Then, a first photoresist layer is formed on the transparent substrate, and the first photoresist layer exposes a second region of the transparent substrate. Next, a first transmitting layer is formed on the transparent substrate and the first photoresist layer. Finally, the first photoresist layer is removed. The first transmitting layer on the first photoresist layer is removed at the same time and the first transmitting layer in the second region of the transparent substrate is remained and a third region of the transparent substrate is exposed. A lift-off process is used in the mask manufacturing method of the present invention to form the transmitting layer.