An accumulated use time measuring method for cargo handling vehicles and a cargo handling vehicle both enable accurate continuation of the use time till a display unit containing a time measuring device is replaced even if the time measuring device fails and prevention of false alteration after shipping while infallibly resetting the time measuring device to zero when the time measure device is shipped from the factory. The function units such as a display unit and a control unit of the cargo handling vehicle each include a time measuring device and a storage device. A synchronization mode in which the difference between the accumulated use times of both devices is made the same and a synchronization inhibition mode in which the accumulated use times are not changed and the time measurement is continued are provided. The accumulated use times are communicated between the function units, and the accumulated use time of the cargo handling vehicle and the absolute value of the difference between the accumulated use times of both measuring devices of the function units are taken into consideration. The corresponding mode is selected from the two modes, and thereby the time measurement using the accumulated use time stored in the storage device is carried out in the selected mode.