A hydraulic control unit for an automatic transmission having a plurality of power transmitting paths and a plurality of engaging clutches and/or brakes for selecting any one of the transmitting paths to set a gear position. The unit comprises a regulator valve for producing a line pressure, an operating pressure control valve for producing an operating pressure supplied to the engaging clutch or brake by regulating the line pressure from the regulator valve, and a line pressure switching valve for making the line pressure produced by the regulator valve low at a specified gear position when a target operating pressure set by the operating pressure control valve is lower than a specified value and making the line pressure high when the target operating pressure is higher than the specified value.