Fuel vapor treatment apparatus

A fuel vapor treatment apparatus that includes a purge valve for controlling a quantity of fuel vapor purged from a canister. The apparatus also includes a controlling device that drives the purge valve based upon flow characteristic of the purge valve to a control amount for driving the purge valve to control a flow quantity of fluid flowing in the purge valve. The apparatus additionally includes a purge switching valve for switching communication of the purge valve between the canister and atmosphere. Furthermore, the apparatus includes a measuring device, which measures fluid pressure produced by opening the purge valve. The apparatus also includes a correcting device, which controls the purge switching valve and corrects the flow characteristic based upon pressure measured by the measuring device when the purge valve and the atmosphere communicate and based on the control amount in which the purge valve controlling device drives the purge valve.