A vehicular automatic transmission comprising: a plurality of engagement devices (B1, B2, C1, C2, C3, C4) configured to realize a plurality of gear positions of the vehicular automatic transmission, according to a combination of engaged and released states of the plurality of engagement devices (B1, B2, C1, C2, C3, C4); and a plurality of planetary gear sets (36, 38, 40), each of the planetary gear sets (36, 38, 40) including rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3), at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) of one of the plurality of planetary gear sets (36, 38, 40) being coupled to one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) of another planetary gear set or one of the engagement devices (B1, B2, C1, C2, C3, C4), via a spline engagement portion, each of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) other than the at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion being coupled to another rotating element or a non-rotary member directly or via one of the engagement devices (B1, B2, C1, C2, C3, C4), characterized in that the at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion is configured to be co-rotated with no torque transmitted via the spline engagement portion, when the automatic transmission is placed in a predetermined gear position as one of the plurality of gear positions; in that said at least one rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion overlaps a part of said one of the other rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) and the engagement device (B1, B2, C1, C2, C3, C4) to which said at least one rotating element is coupled via the spline engagement portion, as viewed in a radial direction of the vehicular automatic transmission; and in that the vehicular automatic transmission comprises a tolerance ring which is mounted in a portion different from the spline engagement portion, such that the tolerance ring is in contact with said at least one rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion, and a part of said one of the other rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) and the engagement device (B1, B2, C1, C2, C3, C4) and said tolerance ring provides sliding resistance to restrict relative rotation between said at least one rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion, and said one of the other rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) and the engagement device (B1, B2, C1, C2, C3, C4). a plurality of engagement devices (B1, B2, C1, C2, C3, C4) configured to realize a plurality of gear positions of the vehicular automatic transmission, according to a combination of engaged and released states of the plurality of engagement devices (B1, B2, C1, C2, C3, C4); and a plurality of planetary gear sets (36, 38, 40), each of the planetary gear sets (36, 38, 40) including rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3), at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) of one of the plurality of planetary gear sets (36, 38, 40) being coupled to one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) of another planetary gear set or one of the engagement devices (B1, B2, C1, C2, C3, C4), via a spline engagement portion, each of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) other than the at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion being coupled to another rotating element or a non-rotary member directly or via one of the engagement devices (B1, B2, C1, C2, C3, C4), characterized in that the at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion is configured to be co-rotated with no torque transmitted via the spline engagement portion, when the automatic transmission is placed in a predetermined gear position as one of the plurality of gear positions; in that said at least one rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion overlaps a part of said one of the other rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) and the engagement device (B1, B2, C1, C2, C3, C4) to which said at least one rotating element is coupled via the spline engagement portion, as viewed in a radial direction of the vehicular automatic transmission; and in that the vehicular automatic transmission comprises a tolerance ring which is mounted in a portion different from the spline engagement portion, such that the tolerance ring is in contact with said at least one rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion, and a part of said one of the other rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) and the engagement device (B1, B2, C1, C2, C3, C4) and said tolerance ring provides sliding resistance to restrict relative rotation between said at least one rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion, and said one of the other rotating element (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) and the engagement device (B1, B2, C1, C2, C3, C4).