Oil pressure control system for automatic transmission

An oil pressure control system for an automatic transmission for executing a downshift by disengaging a first frictional engagement element and engaging a second frictional engagement element, comprising:

• downshift decide means for deciding that said downshift should be executed:
• first oil pressure control means for decreasing an oil pressure of said first frictional engagement element and increasing an oil pressure of said second frictional engagement element when said downshift should be executed;
• first condition decide means for deciding that a predetermined first condition is satisfied after a start of a downshift;
• oil pressure raise means for gradually raising the oil pressure of said first frictional engagement element and increasing a rising rate of the oil pressure of said second frictional engagement element when it is decided that said first condition is satisfied;
• second condition decide means for deciding that a second condition is satisfied;
• and
• second oil pressure control means for decreasing the oil pressure of said first frictional engagement element gradually and further increasing the rising rate of the oil pressure of said second frictional engagement element.