A motor driving device includes: an insulation resistance measuring unit configured to measure insulation resistance of a motor selected as a measurement target to thereby measure the insulation resistance of each of the multiple motors; a measurement interrupting unit configured to interrupt measurement of insulation resistance if a measurement interrupt condition is established; a storage unit configured to store information indicating the motor selected as the measurement target at the time of interruption of the measurement of insulation resistance; and a measurement resuming unit configured to, when measurement is resumed, resume measurement of the insulation resistance sequentially from the motor that had been selected as the measurement target when the measurement was interrupted, based on the information stored in the storage unit.