A spherical lens surface processing method, the method including the steps of: forming a contact state in which a rotating cup-shaped grinding stone (9, 9A, 9B) is brought into contact at a predetermined pressure with a lens surface of a glass lens (5, 5A, 5B) to be processed; and while maintaining the contact state, forming a state of sphere center oscillation in which the cup-shaped grinding stone (9, 9A, 9B) oscillates along the lens surface centered on a sphere center as an oscillation center, and grinding the lens surface to a spherical surface having a predetermined surface precision and center thickness; wherein, in the state of sphere center oscillation, a distance from the oscillation center to a contact point where the cup-shaped grinding stone (9, 9A, 9B) makes contact with the lens surface is set to be equal to a radius of the sphere surface; and when a cross-sectional plane is envisioned, which is a cross-section of the lens (5, 5A, 5B) and the cup-shaped grinding stone (9, 9A, 9B) cut along a vertical plane including a distance and a grinding stone center axis, an oscillation range of the spherical center oscillation is set so that, in the cross-sectional plane, an edge end on one side of the cup-shaped grinding stone (9, 9A, 9B) that contacts the lens surface moves past a lens center along the lens surface, and that an edge end on the other side of the cup-shaped grinding stone (9, 9A, 9B) that contacts the lens surface moves from the lens surface to a position off an outer peripheral edge of the lens surface, and wherein, at the start of grinding in the state of the spherical center oscillation, the lens (5, 5A, 5B) is forcibly rotated by rotational force, which is transmitted via a motive power transmission path having a one-way clutch, at a lesser speed than the cup-shaped grinding stone (9, 9A, 9B); as grinding proceeds, a torque causing the lens (5, 5A, 5B) to rotate due to a frictional force between the lens (5, 5A, 5B) and the cup-shaped grinding stone (9, 9A, 9B) increases; when a rotational speed of a dependent rotation of the lens (5, 5A, 5B), which is caused by the torque, exceeds a forced rotational speed, the motive power transmission path is cut off by an operation of the one-way clutch; and, the lens (5, 5A, 5B) switches from a forced rotation state to a dependent rotation state caused by the cup-shaped grinding stone (9, 9A, 9B). forming a contact state in which a rotating cup-shaped grinding stone (9, 9A, 9B) is brought into contact at a predetermined pressure with a lens surface of a glass lens (5, 5A, 5B) to be processed; and while maintaining the contact state, forming a state of sphere center oscillation in which the cup-shaped grinding stone (9, 9A, 9B) oscillates along the lens surface centered on a sphere center as an oscillation center, and grinding the lens surface to a spherical surface having a predetermined surface precision and center thickness; wherein, in the state of sphere center oscillation, a distance from the oscillation center to a contact point where the cup-shaped grinding stone (9, 9A, 9B) makes contact with the lens surface is set to be equal to a radius of the sphere surface; and when a cross-sectional plane is envisioned, which is a cross-section of the lens (5, 5A, 5B) and the cup-shaped grinding stone (9, 9A, 9B) cut along a vertical plane including a distance and a grinding stone center axis, an oscillation range of the spherical center oscillation is set so that, in the cross-sectional plane, an edge end on one side of the cup-shaped grinding stone (9, 9A, 9B) that contacts the lens surface moves past a lens center along the lens surface, and that an edge end on the other side of the cup-shaped grinding stone (9, 9A, 9B) that contacts the lens surface moves from the lens surface to a position off an outer peripheral edge of the lens surface, and wherein, at the start of grinding in the state of the spherical center oscillation, the lens (5, 5A, 5B) is forcibly rotated by rotational force, which is transmitted via a motive power transmission path having a one-way clutch, at a lesser speed than the cup-shaped grinding stone (9, 9A, 9B); as grinding proceeds, a torque causing the lens (5, 5A, 5B) to rotate due to a frictional force between the lens (5, 5A, 5B) and the cup-shaped grinding stone (9, 9A, 9B) increases; when a rotational speed of a dependent rotation of the lens (5, 5A, 5B), which is caused by the torque, exceeds a forced rotational speed, the motive power transmission path is cut off by an operation of the one-way clutch; and, the lens (5, 5A, 5B) switches from a forced rotation state to a dependent rotation state caused by the cup-shaped grinding stone (9, 9A, 9B).