To provide a hydraulic control device of an automatic transmission capable of reducing engagement shocks by suitably adjusting a predetermined control hydraulic pressure according to an environmental change relating to a magnitude of an output of an internal combustion engine.

A transmission shock generated actually is detected by engagement shock detection means 128, and an engagement hydraulic pressure Pt is changed to reduce the magnitude of the transmission shock, and converged to the hydraulic pressure, at which the transmission shock becomes minimum. Also, when a transmission number F after the environmental change is detected is small, a changed amount of the engagement hydraulic pressure Pt for one time is made larger than the case where the number is large, and therefore, the hydraulic pressure can be quickly made close to the hydraulic pressure, in which the transmission shock becomes small immediately after the environmental change which leads to a high possibility that the transmission shock becomes large.