To provide a spline connection structure capable of improving installation accuracy in the rotational direction of a cylinder shaft and a rotary shaft.

In a range switching device 10, an output shaft 63 of an actuator 60 and a control shaft 52 of a detent lever 51 are fitted by a spline. A piston 73 energized toward the output shaft 63 side by a coil spring 75 is arranged on the control shaft 52 of the detent lever 51. An engaging hole 74 meshing with a pin 73 energized by the coil spring 75, is arranged on the output shaft 63 of the actuator 60.