A motor drive system comprising: a rechargeable power storage device; a power control unit configured to drive a motor (MG1, MG2) by using electric power supplied from said power storage device; an open/close device disposed on a power line connecting said power storage device to said power control unit; a first interlock mechanism configured to be activated in response to transition to an operable state of an interruption device for interrupting an output of said power storage device; a second interlock mechanism configured to be activated in response to transition to an openable state of a case containing said power control unit; and a control device for controlling said power control unit and said first and second interlock mechanisms (160, 210) and for detecting an opened/closed state of said first and second interlock mechanisms (160, 210), said power control unit including an inverter for converting the electric power from said power storage device to electric power for driving said motor (MG1, MG2), and a capacitor connected to a terminal of said inverter on the side of said power storage device, said control device being configured to perform, when said first interlock mechanism is activated, a first process of opening said open/close device after shutting down said power control unit, and perform, when said second interlock mechanism is activated, either one of said first process and a second process depending on a counter electromotive voltage generated by said motor (MG1, MG2), wherein said second process is driving said power control unit so as to convert the counter electromotive voltage generated by said motor (MG1, MG2) into a DC voltage by said inverter and to output said DC voltage to the power storage device, and thereafter opening said open/close device. a rechargeable power storage device; a power control unit configured to drive a motor (MG1, MG2) by using electric power supplied from said power storage device; an open/close device disposed on a power line connecting said power storage device to said power control unit; a first interlock mechanism configured to be activated in response to transition to an operable state of an interruption device for interrupting an output of said power storage device; a second interlock mechanism configured to be activated in response to transition to an openable state of a case containing said power control unit; and a control device for controlling said power control unit and said first and second interlock mechanisms (160, 210) and for detecting an opened/closed state of said first and second interlock mechanisms (160, 210), said power control unit including an inverter for converting the electric power from said power storage device to electric power for driving said motor (MG1, MG2), and a capacitor connected to a terminal of said inverter on the side of said power storage device, an inverter for converting the electric power from said power storage device to electric power for driving said motor (MG1, MG2), and a capacitor connected to a terminal of said inverter on the side of said power storage device, said control device being configured to perform, when said first interlock mechanism is activated, a first process of opening said open/close device after shutting down said power control unit, and perform, when said second interlock mechanism is activated, either one of said first process and a second process depending on a counter electromotive voltage generated by said motor (MG1, MG2), wherein said second process is driving said power control unit so as to convert the counter electromotive voltage generated by said motor (MG1, MG2) into a DC voltage by said inverter and to output said DC voltage to the power storage device, and thereafter opening said open/close device.