Abstract

In a line pressure control device of an automatic transmission for vehicle a circuit is provided for generating a target line pressure signal corresponding an actually measured load signal obtained from an engine load sensor. A line pressure sensor generates an actually measured line pressure signal corresponding to the line pressure. A converter converts the target line pressure signal and the actually measured line pressure signal into upper limit line pressure signals and lower limit line pressure signals which are set given amounts above and below the target signal and the actually measured signal respectively. A decision circuit compares the upper and lower limit line pressure signals drives and properly driving and controls the hydraulic pressure adjusting valve in accordance with the result of the comparison.