PURPOSE: To rotate a spool at the position which corresponds to high speed step when an actuator is in failure and position the spool in axial direction in a rotary valve for automatic transmission which accommodates the free- rotating spool in the inside of a valve housing.

CONSTITUTION: A spool 7 which is accommodated inside a valve housing 1 and rotated and driven by a pulse motor 6 is energized to rotate by a coil spring 22 whose one end is engaged with a pin 20 which is provided in the spool 7 and whose another end is engaged by a bolt 21 which is screwed in the valve housing 1. When drive force is reduced due to failure of the pulse motor 6, the spool 7 rotates at the predetermined position due to resilient force of the coil spring 22 to change over automatic transmission into high speed step or neutral step. The coil spring 22 is also energized in the direction where it presses the spool 7 on a thrust bearing 10. Thus, the spool 7 is positioned in axial direction.