A mileage display system includes a control unit operatively connected to an ignition switch of a motorcycle that obtains the accumulated mileage by accumulating a pulse signal produced according to running of the motorcycle. The control unit records odometer data in an EEPROM. The control unit also reads the odometer data recorded in the EEPROM when the ignition switch is operated. If the odometer data exceeds the maximum value to be displayed on an odometer (for example, 99999), the control unit displays on the odometer for a predetermined period of time a numeric value of digits of higher order than the predetermined number of display digits of the odometer data. The mileage display system displays an accurate, accumulated distance traveled or accumulated mileage, after the mileage overflows by exceeding a maximum display value as established by a predetermined number of display digits.