A method for manufacturing a disk-shaped glass substrate, the disk-shaped glass substrate being for cutting out one or more glass substrates, the method comprising: preparing a disk-shaped glass blank having a refractive index of 1.60 or more, the disk-shaped glass blank having a first substrate thickness, the disk-shaped glass blank being a glass blank having two first circular main surfaces (101c, 101d) and a first outer circumferential edge surface which intersect at a right angle respectively at outer edge portions (104c, 104d); chamfering the outer edge portions (104c, 104d) of the two first circular main surfaces (101c, 101d) of the disk-shaped glass blank to produce a chamfered disk-shaped glass blank having two second circular main surfaces (101e, 101f) and first chamfering surfaces (103c, 103d) that connect the two second circular main surfaces (101e, 101f) and a second outer circumferential edge surface having a second substrate thickness, wherein the chamfered disk-shaped glass blank, excluding the second outer circumferential edge surface and the first chamfering surfaces (103c, 103d), has the first substrate thickness, wherein the following equation t1×0.15<t2<t1×0.4 is satisfied, the first chamfering surfaces (103c, 103d), forming straight lines when viewed from a side, being formed on the disk-shaped glass blank; grinding the two second circular main surfaces (101e, 101f) of the chamfered disk-shaped glass blank, using a double-side grinding apparatus to produce a ground disk-shaped glass blank having two third circular main surfaces; and polishing the two third circular main surfaces of the ground disk-shaped glass blank, using a double-side polishing apparatus to produce the disk-shaped glass substrate, wherein the disk-shaped glass substrate produced through the polishing has a third substrate thickness, excluding the second outer circumferential edge surface and the second chamfering surfaces (103a, 103b) of the disk-shaped glass substrate, and the following equation t3×0.5<t2 is satisfied, and wherein, in the polishing, the disk-shaped glass substrate having a root mean square roughness Rq of 0.4 nm or less is produced by polishing the two third circular main surfaces of the ground disk-shaped glass blank. preparing a disk-shaped glass blank having a refractive index of 1.60 or more, the disk-shaped glass blank having a first substrate thickness, the disk-shaped glass blank being a glass blank having two first circular main surfaces (101c, 101d) and a first outer circumferential edge surface which intersect at a right angle respectively at outer edge portions (104c, 104d); chamfering the outer edge portions (104c, 104d) of the two first circular main surfaces (101c, 101d) of the disk-shaped glass blank to produce a chamfered disk-shaped glass blank having two second circular main surfaces (101e, 101f) and first chamfering surfaces (103c, 103d) that connect the two second circular main surfaces (101e, 101f) and a second outer circumferential edge surface having a second substrate thickness, wherein the chamfered disk-shaped glass blank, excluding the second outer circumferential edge surface and the first chamfering surfaces (103c, 103d), has the first substrate thickness, wherein the following equation t1×0.15<t2<t1×0.4 is satisfied, the first chamfering surfaces (103c, 103d), forming straight lines when viewed from a side, being formed on the disk-shaped glass blank; grinding the two second circular main surfaces (101e, 101f) of the chamfered disk-shaped glass blank, using a double-side grinding apparatus to produce a ground disk-shaped glass blank having two third circular main surfaces; and polishing the two third circular main surfaces of the ground disk-shaped glass blank, using a double-side polishing apparatus to produce the disk-shaped glass substrate, wherein the disk-shaped glass substrate produced through the polishing has a third substrate thickness, excluding the second outer circumferential edge surface and the second chamfering surfaces (103a, 103b) of the disk-shaped glass substrate, and the following equation t3×0.5<t2 is satisfied, and wherein, in the polishing, the disk-shaped glass substrate having a root mean square roughness Rq of 0.4 nm or less is produced by polishing the two third circular main surfaces of the ground disk-shaped glass blank.