Oil pressure control device of automatic transmission

An oil pressure control device for an automatic transmission, comprising:

• a hydraulic servo that engages and disengages a friction engagement element;
• a pressure adjusting unit that adjusts an original pressure from an oil pressure source to provide an adjusted oil pressure and supplies the adjusted oil pressure to the hydraulic servo, the pressure adjusting unit having a first port to which the original pressure is supplied, an output port for outputting the adjusted oil pressure, and a second port for draining oil during a pressure adjustment;
• a changeover valve having a first input port to which the original pressure is supplied, a drain port, and an original pressure output port that is selectively connectable to the first input port or the drain port;
• and
• a connecting oil passage connecting the first input port and the oil pressure source,
• wherein the second port of the pressure adjusting unit is connectable to the connecting oil passage via the original pressure output port.