A shaft member (1, 1a, 1b, 1c, 1d, 1e) comprising: an outer peripheral surface (2, 2a, 2b); at least one axial side surface (3a, 3b) facing an axial direction; a chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) formed at a connection portion between an axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) and an outer peripheral edge (6a, 6b, 6c) of the axial side surface; and a processing target portion formed on at least a part of the outer peripheral surface (2, 2a, 2b), wherein: the chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) includes at least one supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) disposed at an axially intermediate portion of the chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) and inclined radially outward as approaching the processing target portion in the axial direction, and a connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) or step (18a, 18b, 18c, 18d, 18e, 18f, 18g) of the chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) connects an axial end edge of the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) with the axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) or the outer peripheral edge (6a, 6b, 6c) of the axial side surface, the shaft member (1, 1a, 1b, 1c, 1d, 1e) characterized in that: the axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) and the outer peripheral edge (6a, 6b, 6c) of the axial side surface are located radially inward of a tangent line at an axially intermediate portion of the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f), in a cross section in the axial direction, the connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) or the step portion (18a, 18b, 18c, 18d, 18e, 18f, 18g) is configured to absorb the elongation of the shaft member (1, 1a, 1b, 1c, 1d, 1e) when the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) is pressed in the radial direction, wherein the connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) is a convex curved surface having an arc-shaped generatrix inclined radially outward as approaching the other axial side. an outer peripheral surface (2, 2a, 2b); at least one axial side surface (3a, 3b) facing an axial direction; a chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) formed at a connection portion between an axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) and an outer peripheral edge (6a, 6b, 6c) of the axial side surface; and a processing target portion formed on at least a part of the outer peripheral surface (2, 2a, 2b), the chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) includes at least one supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) disposed at an axially intermediate portion of the chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) and inclined radially outward as approaching the processing target portion in the axial direction, and a connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) or step (18a, 18b, 18c, 18d, 18e, 18f, 18g) of the chamfered portion (7a, 7b, 7c, 7d, 7e, 7f) connects an axial end edge of the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) with the axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) or the outer peripheral edge (6a, 6b, 6c) of the axial side surface, the shaft member (1, 1a, 1b, 1c, 1d, 1e) characterized in that: the axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) and the outer peripheral edge (6a, 6b, 6c) of the axial side surface are located radially inward of a tangent line at an axially intermediate portion of the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f), in a cross section in the axial direction, the connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) or the step portion (18a, 18b, 18c, 18d, 18e, 18f, 18g) is configured to absorb the elongation of the shaft member (1, 1a, 1b, 1c, 1d, 1e) when the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) is pressed in the radial direction, the axial end edge (5a, 5b, 5c) of the outer peripheral surface (2, 2a, 2b) and the outer peripheral edge (6a, 6b, 6c) of the axial side surface are located radially inward of a tangent line at an axially intermediate portion of the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f), in a cross section in the axial direction, the connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) or the step portion (18a, 18b, 18c, 18d, 18e, 18f, 18g) is configured to absorb the elongation of the shaft member (1, 1a, 1b, 1c, 1d, 1e) when the supported surface portion (9a, 9b, 9c, 9d, 9e, 9f) is pressed in the radial direction, wherein the connection inclined surface portion (10a1, 10a2, 10b1, 10b2, 10c1, 10c2) is a convex curved surface having an arc-shaped generatrix inclined radially outward as approaching the other axial side.