To provide a phase shift mask production method that improves the alignment accuracy of patterns and reduced in processing cost.

A photoresist layer is formed on a shielding layer in such a way that the photoresist layer has a vertical side wall, a deposited layer is uniformly formed on the photoresist layer and the shielding layer surrounding the photoresist layer, and the deposited layer is silylanized. In order to form a spacer on the vertical side wall, the deposited layer on the photoresist layer and the shielding layer surrounding the photoresist layer is removed and the deposited layer covering the top of the vertical side wall of the photoresist layer is partially removed. The shielding layer not covered with the photoresist layer and the spacer and a phase shifter layer are vertically removed and spacer and the shielding layer under the spacer are vertically removed. The photoresist layer is thoroughly removed so as to complete the objective phase shift mask.