Method of controlling a forklift and forklift

Variable displacement traveling hydraulic pump driven by the engine, a closed circuit is formed between the travel hydraulic pump is driven by a hydraulic motor and a hydraulic motor driven by hydraulic fluid discharged from the travel hydraulic pump a forklift comprising a drive wheel that, in order to change the responsiveness of the travel hydraulic pump to the operation amount of the accelerator operating part, and a first cut-off frequency determined from the accelerator opening the accelerator opening sensor has detected, by using the second cutoff frequency which is a first cut-off frequency determined from the corrected accelerator opening determined in the previous time required, the larger the, the accelerator opening the accelerator opening sensor has detected corrected obtains the accelerator opening degree.