| 摘要 |
PROBLEM TO BE SOLVED: To suppress a disturbance of an air flow in an area around an exterior circumferential side end part of a magnetic disk, and to suppress fluttering.SOLUTION: A magnetic disk glass substrate comprises: a pair of principal surfaces 11p and 12p; and an end face. The end face has: a side wall face 11w; and chamfered faces 11c and 12c intervening between the principal surfaces and the side wall face. Circularity of the end face on an exterior circumferential side is equal to or less than 1.5 μm. A contour line in a circumferential direction at positions of two points of 200 μm away from each other in a plate thickness direction on the side wall face on the exterior circumferential side is respectively acquired, to let a middle point between centers of two least square circles to be respectively obtained from the contour lines be a middle point A, and a contour line in the circumferential direction is respectively acquired at a position of a center of the plate thickness direction on two chamfered faces on the exterior circumferential side, to let a center to be obtained from one chamfered face of centers of least square circles to be obtained from the contour lines be a center B, and let a center obtained from the other chamfered face thereof be a center C, a sum of a distance between the middle point A and the center B and a distance between the middle point A and the center C is equal to or less than 1 μm. |
