A diagnostic apparatus to diagnose a drive motor used in an electric vehicle that is driven by the motor, comprising: a start-up abnormality detection section to detect a coil temperature of a motor coil and a coil resistance of the motor coil during a non-traveling time, in which an electric power is supplied to a control unit to control the entirety of the vehicle and not supplied to the motor, and then to determine an occurrence of an abnormality in the motor coil in the event that the coil temperature exceeds a threshold value or the coil resistance exceeds a threshold value; a travel abnormality detection section to detect a rotation number of the motor, a motor applied voltage and a motor current during a traveling of the vehicle and then to determine an occurrence of the abnormality in the motor coil in the event that a relation between the motor applied voltage and the motor current relative to the rotation numbers of the motor fails to fall within a predetermined range; and a unit to drive the motor comprises an inverter to convert a direct current power into an alternating current power that is used in driving the motor, wherein: i) the start-up abnormality detection section is configured to apply a voltage to electric contact points between the motor coil of each phase of the motor and the inverter and then to measure the coil resistance of the motor coil of each phase from a measured value of an electric current between the electric contact points; or ii) the unit to drive the motor further comprises a switch element to selectively open and close an electric connection between the motor and the inverter; and the start-up abnormality detection section is configured to open the switch element to sequentially apply a voltage and then to measure the coil resistance of the motor coil of each phase from a measured value of an electric current of the motor coil of each phase to which the voltage is applied, and wherein the diagnostic apparatus further comprising a thermister positioned proximate to the motor coil, wherein the start-up abnormality detection section includes a correction block to correct the measured coil resistance in accordance with a coil temperature outputted from the thermister. a start-up abnormality detection section to detect a coil temperature of a motor coil and a coil resistance of the motor coil during a non-traveling time, in which an electric power is supplied to a control unit to control the entirety of the vehicle and not supplied to the motor, and then to determine an occurrence of an abnormality in the motor coil in the event that the coil temperature exceeds a threshold value or the coil resistance exceeds a threshold value; a travel abnormality detection section to detect a rotation number of the motor, a motor applied voltage and a motor current during a traveling of the vehicle and then to determine an occurrence of the abnormality in the motor coil in the event that a relation between the motor applied voltage and the motor current relative to the rotation numbers of the motor fails to fall within a predetermined range; and a unit to drive the motor comprises an inverter to convert a direct current power into an alternating current power that is used in driving the motor, wherein: i) the start-up abnormality detection section is configured to apply a voltage to electric contact points between the motor coil of each phase of the motor and the inverter and then to measure the coil resistance of the motor coil of each phase from a measured value of an electric current between the electric contact points; or ii) the unit to drive the motor further comprises a switch element to selectively open and close an electric connection between the motor and the inverter; and i) the start-up abnormality detection section is configured to apply a voltage to electric contact points between the motor coil of each phase of the motor and the inverter and then to measure the coil resistance of the motor coil of each phase from a measured value of an electric current between the electric contact points; or ii) the unit to drive the motor further comprises a switch element to selectively open and close an electric connection between the motor and the inverter; and the start-up abnormality detection section is configured to open the switch element to sequentially apply a voltage and then to measure the coil resistance of the motor coil of each phase from a measured value of an electric current of the motor coil of each phase to which the voltage is applied, and wherein the diagnostic apparatus further comprising a thermister positioned proximate to the motor coil, wherein the start-up abnormality detection section includes a correction block to correct the measured coil resistance in accordance with a coil temperature outputted from the thermister.