A motor driving system comprising: a plurality of motors ( MG1, MG2, MGR); a motor driving device ( 40, 50, 60) provided to correspond to each of said plurality of motors ( MG1, MG2, MGR) to generate motor driving current for driving a corresponding motor of said plurality of motors ( MG1, MG2, MGR) by switching operations of power semiconductor elements; a current detector ( 41, 42 / 51, 52 / 61, 62) provided to correspond to each said motor driving device ( 40, 50, 60) to detect the corresponding motor driving current; and a control circuit for controlling operation of each said motor driving device ( 40, 50, 60) based on at least detected current by each said current detector ( 41, 42 / 51, 52 / 61, 62), said control circuit including: first determining means configured to determine a non-energized state in each said current detector ( 41, 42 / 51, 52 / 61, 62); and second determining means configured to determine, in the current detector ( 41, 42 / 51, 52 / 61, 62) determined to be in said non-energized state by said first determining means, a noise state from the remaining motor driving device ( 40, 50, 60) other than the motor driving device ( 40, 50, 60) corresponding to said current detector ( 41, 42 / 51, 52 / 61, 62); characterized by zero point adjustment means ( S120, S130) configured to carry out zero point adjustment of said current detector ( 41, 42 / 51, 52 / 61, 62) determined to be in said non-energized state according to determination by said second determining means, wherein said second determining means is configured to allow execution of said zero point adjustment of the current detector ( 41, 42 / 51, 52 / 61, 62) by said zero point adjustment means ( S120, S120, S130) when switching operation in said remaining motor driving device ( 40, 50, 60) is at a stop, wherein said motor driving system is mounted on a vehicle, said plurality of motors ( MG1, MG2, MGR) are AC motors each configured to generate driving force for said vehicle, and each said motor driving device ( 40, 50, 60) is an inverter circuit configured to convert DC electric power into driving electric power for a corresponding one of said AC motors, and said second determining means is configured to allow execution of said zero point adjustment in a period in which each said inverter is shut down according to a shift position selection in said vehicle. a plurality of motors ( MG1, MG2, MGR); a motor driving device ( 40, 50, 60) provided to correspond to each of said plurality of motors ( MG1, MG2, MGR) to generate motor driving current for driving a corresponding motor of said plurality of motors ( MG1, MG2, MGR) by switching operations of power semiconductor elements; a current detector ( 41, 42 / 51, 52 / 61, 62) provided to correspond to each said motor driving device ( 40, 50, 60) to detect the corresponding motor driving current; and a control circuit for controlling operation of each said motor driving device ( 40, 50, 60) based on at least detected current by each said current detector ( 41, 42 / 51, 52 / 61, 62), said control circuit including: first determining means configured to determine a non-energized state in each said current detector ( 41, 42 / 51, 52 / 61, 62); and second determining means configured to determine, in the current detector ( 41, 42 / 51, 52 / 61, 62) determined to be in said non-energized state by said first determining means, a noise state from the remaining motor driving device ( 40, 50, 60) other than the motor driving device ( 40, 50, 60) corresponding to said current detector ( 41, 42 / 51, 52 / 61, 62); first determining means configured to determine a non-energized state in each said current detector ( 41, 42 / 51, 52 / 61, 62); and second determining means configured to determine, in the current detector ( 41, 42 / 51, 52 / 61, 62) determined to be in said non-energized state by said first determining means, a noise state from the remaining motor driving device ( 40, 50, 60) other than the motor driving device ( 40, 50, 60) corresponding to said current detector ( 41, 42 / 51, 52 / 61, 62); characterized by zero point adjustment means ( S120, S130) configured to carry out zero point adjustment of said current detector ( 41, 42 / 51, 52 / 61, 62) determined to be in said non-energized state according to determination by said second determining means, wherein said second determining means is configured to allow execution of said zero point adjustment of the current detector ( 41, 42 / 51, 52 / 61, 62) by said zero point adjustment means ( S120, S120, S130) when switching operation in said remaining motor driving device ( 40, 50, 60) is at a stop, wherein said motor driving system is mounted on a vehicle, said plurality of motors ( MG1, MG2, MGR) are AC motors each configured to generate driving force for said vehicle, and each said motor driving device ( 40, 50, 60) is an inverter circuit configured to convert DC electric power into driving electric power for a corresponding one of said AC motors, and said second determining means is configured to allow execution of said zero point adjustment in a period in which each said inverter is shut down according to a shift position selection in said vehicle.