PURPOSE: To avoid the generation of the interlocked state by installing a sequence valve which permits the supply of hydraulic pressure into a low speed stage side frictional element, when the hydraulic pressure of the high speed stage side frictional element of a subtransmission mechanism lowers to a prescribed value.

CONSTITUTION: When the spool 102 of a shift valve 100 is switched to a descent position by a shift solenoid 118, in order to switch a subspeed change mechanism to a deceleration state, the second oil passage 110 is drained, and the hydraulic pressure supplied into a direct clutch 32 gradually lowers through a one-way orifice 124 and an accumulator 128. When the stroke of the piston 136 of the accumulator 128 is completed, the hydraulic pressure of the fourth oil passage 126 and a pilot port 134 sharply lowers, and the clutch 32 is perfectly released. At the same time, the spool 146 of a sequence valve 132 is moved leftward by a spring 148, and the line pressure in the first oil passage 112 is supplied into a reduction brake 33. Therefore, in any state, the generation of the interlocked state can be avoided.