An electrostatic chuck that enables high speed and high quality processing of a plate to be processed, and in which the weight of a base member is reduced and the strength thereof increased so as to maintain the flatness of the base member and prevent the plate to be processed from falling; a glass substrate processing method; and said glass substrate. An electrostatic chuck (1) provided with a base member (2) and an electrostatic suction layer (3). The base member (2) is formed by a lower-surface plate (20), side-surface plates (21-24), and an upper-surface plate (25), and has a part (4) for a plurality of individual structures configured therein. The part (4) for a plurality of individual structures has a honeycomb structure that is caused by regular hexagonal tubes (40) and enables the weight of the base member (2) to be reduced and the strength thereof increased.