Provided is a diagnosis method of appropriately recognizing a state of a rolling surface of a track member of a rolling guide device or a lubrication state of rolling elements using a sensor mounted to the rolling guide device. The diagnosis method is applied to a rolling guide device including: a track member having a rolling surface extending along a longitudinal direction of the track member; and a moving member, which is assembled to the track member through intermediation of a plurality of rolling elements configured to roll on the rolling surface so that the moving member is movable along the track member, and has an endless circulation path for the rolling elements. The diagnosis method includes: detecting a moving speed of the moving member relative to the track member while detecting relative vibration displacement of the moving member relative to the track member using a vibration sensor mounted to the moving member; and diagnosing a running state of the moving member relative to the track member based on those detection results.