PURPOSE: To provide a photomask glass substrate, a photomask blank, a photomask, and the holding method thereof by which the difficulty of fixing and holding accompanied by the increase of the size and the weight of the photomask is released when the substrate is held and carried, and the convenience of a handling jig and device is not allowed to be damaged.

CONSTITUTION: At least two or more of opening portions P1 to P5 are provided in the side faces of a photomask glass substrate 1, a photomask blank, a photomask substrate 1. There are two kinds of methods, in one case of which the opening portions P1 to P5 are independent so as not to reach the one side face of a front or back face of the substrate 1, and in the other case of which the one ends of the opening portions reach the one side face of the front or back face of the substrate 1. Utilizing the openings P1 to P5, the photomask substrate can be held and moved easily using a holding jig. The openings P1 to P5 also act on fixing and holding in the treatment process of the photomask.