To provide a photomask formed with mask patterns with high accuracy.

The method of manufacturing the photomask having a process step of forming a photoresist layer on a transparent substrate element body 1 having a light shielding layer prior to an etching treatment, a process step of forming resist patterns on the light shielding layer by irradiating the photoresist layer with an energy ray to form latent image patterns, then developing the same, a process step of etching the light shielding layer, and a process step of removing the resist patterns, in which the transparent substrate element body 1 is rotated around its center and the energy ray is relatively moved in a diametral direction of the rotation of the transparent substrate element body and the transparent substrate element body is intermittently irradiated with the energy ray to be lined with the irradiation spots of the energy ray.