To provide a measuring method for accurately measuring surface waviness and a device thereof.

This is a measuring method for a surface waviness, specially the surface waviness in a bearing part such as a ball, a roller, and a bearing ring using a control device being contacted to the surface of an object to be inspected so that it can be rotated to the surface. A load control device 6 having a contact region to the object and the same shape as a final bearing unit in the proximity of the contact region is placed in a hydraulic pocket 5 or held in a bearing apparatus so that the device 6 can be rotated to move, and then is loaded with nearly constant force and placed so that the device 6 can cross a surface to be inspected to move with rotating-capability. Also, at least one of converters 8, 13 is placed in order to monitor direct movement of the device 6 or movement through the pocket 5, and a signal corresponding to the surface waviness occurred is generated.