In a fuel supplying controller detecting a clogging of a fuel filter, a timer count portion includes a steady count portion and an unsteady count portion. The steady count portion adds a steady count value to a timer counter in a steady state where a vehicle-state value is less than a threshold. The unsteady count portion adds an unsteady count value that is greater than the steady count value to the timer counter in an unsteady state where the vehicle-state value is greater than or equal to the threshold.