Temperatures of a base, a support member, and a support member are measured, and amounts of linear expansion of the base, the support member, and the support member due to temperature differences from a reference temperature are computed. An amount of linear expansion of a ball screw with respect to the support member is measured. An amount of linear expansion of a lead of the ball screw is computed based on the sum of the aforementioned amounts of linear expansion, and an amount of rotation of the ball screw is adjusted from an amount of rotation of the ball screw at the reference temperature, to an amount of rotation of the ball screw, which corresponds to the amount of linear expansion of the lead at a predetermined temperature.