Abstract: In order to suppress or prevent the occurrence of foreign matter in the manufacture of a semiconductor integrated circuit device by the use of a photo mask constituted in such a manner that a resist film is made to function as a light screening film, inspection or exposure treatment is carried out, when the photo mask 1PA1 has been mounted on a predetermined apparatus such as, e.g., an inspection equipment or aligner, in the state in which a mounting portion 2 of the predetermined apparatus is contacted with that region of a major surface of a mask substrate 1a of the photo mask 1PA1 in which a light shielding pattern 1b and a mask pattern 1mr, each formed of a resist film, on the major surface of the mask substrate 1a do not exist.