the same reference numerals in this specification in the detailed description ordinal numbers are used for distinguishing constituent elements having the same terms and have no specific meanings fig1 is a schematic diagram of a hydraulic pressure supply system according to an exemplary embodiment of the present invention when a low pressure hydraulic pump and a high pressure hydraulic pump are operated normally referring to fig1 a hydraulic pressure supply system according to an exemplary embodiment of the present invention is adapted to supply low hydraulic pressure generated by a low pressure hydraulic pump 2 to a low pressure portion 4 such as a torque converter t c a cooling portion a lubrication portion and to supply high hydraulic pressure generated by a high pressure hydraulic pump 6 to a high pressure portion 8 for operating friction members related to shifting the low hydraulic pressure is a lower pressure facilitating operation of the torque converter t c and cooling and lubrication and the high hydraulic pressure is a high pressure facilitating operation of a plurality of friction members the low hydraulic pressure is generated by the low pressure hydraulic pump 2 and is supplied to the low pressure portion 4 through a switch valve 10 and a low pressure regulator valve 12 the low pressure hydraulic pump 2 as is well known to a person of an ordinary skill in the art is a mechanical pump driven by torque of an engine the low pressure hydraulic pump 2 is connected to an oil pan p through a first input line 14 and discharges the low hydraulic pressure generated by the low pressure hydraulic pump 2 to a first low pressure line 16 the switch valve 10 may be a spool valve and is adapted to be controlled.