A cooling method and cooling apparatus which can reduce thermal deformation of a mobile body of a machine tool is provided. On the front of a column (1), a pair of upper and lower guides (3) is formed, and saddle (7) is suspended on guides (3), saddle (7) being movable left and right. Guiding surface (5) of guide (3) and sliding surface (9) of saddle (7) are slip surface and are in contact with each other. Sliding surfaces (9a, 9b, 9d, 9e) which generate a large amount of heat and need to be cooled are identified in advance by simulation. Fluid pipelines (25) for cooling the identified portions generating higher heat are formed, and a coolant liquid is circulated by being passed from portion (9a) generating less heat toward portion (9e) generating higher heat.