To suppress generation of bending and vibration without damaging the surface of a substrate by sucking and holding a glass substrate by a holding frame forming an opening for transmission and illumination at the center and erecting a plurality of supporting pins supporting a glass plate on an upper surface of a transparent member with rigidity.

By projectingly providing two reference pins 6 and a reference pin 6 on an upper surface front side of a holding frame 1 and an upper surface left side, respectively, and abutting a side surface of a glass plate mounted on a supporting pin 4 on the side surfaces of three reference pins 6, the positioning is performed. On an upper surface right side and an upper surface rear side of the holding frame 1, each one aligning pin 7 is disposed so as to be freely movable in a center direction of the holding frame 1. The aligning pin 7 presses a side surface of a glass substrate 3 mounted on the supporting pin 4 in the center direction of the holding frame 1 by a driving mechanism connected with the lower part. At 8 portions of at the peripheral edge of an opening 1a for irradiating transmission light of the holding frame 1, suction pads 8 are disposed and the glass substrate 3 positioned by the reference pins 6 and the aligning pins 7 is sucked and fixed.