A photomask manufacturing method relating to semiconductor technology is presented. The manufacturing method involves providing a substrate structure comprising an etch material layer, a first sacrificial layer on a portion of the etch material layer, and a photomask layer on an upper surface of the etch material layer and on an upper surface and a side surface of the first sacrificial layer; forming a second sacrificial layer covering the photomask layer on the etch material layer and on the side surface of the first sacrificial layer; etching the photomask layer not covered by the second sacrificial layer to expose the first sacrificial layer; removing the first sacrificial layer and the second sacrificial layer; and removing the photomask layer on the etch material layer. This photomask manufacturing method offers a photomask of better symmetricity than those from conventional methods.