A motor driving device for driving a first permanent magnet synchronous motor and a second permanent magnet synchronous motor , the motor driving device comprising: a converter to generate a direct-current voltage; an inverter to generate a three-phase alternating-current voltage from the direct-current voltage; three first power lines to supply the three-phase alternating-current voltage to the first permanent magnet synchronous motor ; three second power lines to supply the three-phase alternating-current voltage to the second permanent magnet synchronous motor ; at least two disconnection contactors to switch between connection and disconnection of each of at least two of the three second power lines ; characterized by at least two short-circuit contactors to switch between connection and disconnection between the two second power lines of each of at least two of pairs of the three second power lines ; a current sensor to detect a current value of a current flowing through the second permanent magnet synchronous motor ; and a controller to control the at least two disconnection contactors and the at least two short-circuit contactors , wherein when stopping driving of the second permanent magnet synchronous motor , the controller switches the at least two disconnection contactors from the connection to the disconnection and switches the at least two short-circuit contactors from the disconnection to the connection, and wherein after the controller switches the at least two short-circuit contactors from the disconnection to the connection, when it is determined that the current value is greater than a predetermined threshold, the controller switches the at least two short-circuit contactors from the connection to the disconnection. a converter to generate a direct-current voltage; an inverter to generate a three-phase alternating-current voltage from the direct-current voltage; three first power lines to supply the three-phase alternating-current voltage to the first permanent magnet synchronous motor ; three second power lines to supply the three-phase alternating-current voltage to the second permanent magnet synchronous motor ; at least two disconnection contactors to switch between connection and disconnection of each of at least two of the three second power lines ; characterized by at least two short-circuit contactors to switch between connection and disconnection between the two second power lines of each of at least two of pairs of the three second power lines ; a current sensor to detect a current value of a current flowing through the second permanent magnet synchronous motor ; and a controller to control the at least two disconnection contactors and the at least two short-circuit contactors , wherein when stopping driving of the second permanent magnet synchronous motor , the controller switches the at least two disconnection contactors from the connection to the disconnection and switches the at least two short-circuit contactors from the disconnection to the connection, and wherein after the controller switches the at least two short-circuit contactors from the disconnection to the connection, when it is determined that the current value is greater than a predetermined threshold, the controller switches the at least two short-circuit contactors from the connection to the disconnection. <EOS>