Abstract: A telescopic shaft includes an inner shaft and a cylindrical outer shaft that are fitted together. A first raceway groove extending in the axial direction is formed in an outer peripheral surface of the inner shaft. A second raceway groove extending in the axial direction and facing the first raceway groove is formed in an inner peripheral surface of the outer shaft. A plurality of balls interposed between the first and second raceway grooves and arranged in a row in the axial direction roll in a first stroke range in the axial direction with respect to the inner shaft and roll in a second stroke range in the axial direction with respect to the outer shaft as the inner and outer shafts move relative to each other in the axial direction. The depth of the first raceway groove decreases from the middle toward both ends of the first stroke range.