To provide a simple man-machine interface which can modify pulse rate with an interactive mode on a display, in compensating disunity of a standard for installed tire size at factory shipment among fork-lift makers, difference of installed tire size at factory shipment for each loading weight system, or traveling distance difference due to changing of an installed tire after its shipment.

The operation controlling device 10 is constituted so as to measure operation condition of a fork-lift, form operation control data 12a on its operation log, and record the operation control data 12a. In this case, a pulse rate setting means 18 which can optionally change and set pulse rate data 18a on convergence rate for converting rotational condition of an axle of the fork-lift to vehicle speed is provided.