Abstract: A mounting structure is provided for a one-way clutch in an automatic transmission of the type that a carrier of a planetary gear mechanism and a casing of the transmission are connected together by way of a one-way clutch allowing the carrier to rotate only in one direction along a central axis of rotation of the planetary gear mechanism. A coupling member coupling the carrier and the one-way clutch to each other is splined at an end portion thereof, which is located on the side of the carrier, with the carrier so as to allow the carrier to slide along the central axis of the rotation. A limiting member is provided to limit the range of sliding movements of the coupling member.