A fuel vapor purging control system is provided. This system includes a fuel vapor collection canister, a purge control valve for controlling a purge flow rate of fuel vapors purged from the canister, a purge air induction passage communicating between the canister and an air inlet port which is exposed to atmospheric pressure, an air pump for supplying pressurized air to the canister through the purge air induction passage, a pressure sensor for detecting negative pressure in an induction system of the engine, and a purge air control unit. When the engine falls to a relatively high load level and the negative pressure becomes smaller than a preselected threshold value, the purge air control unit directs the pressurized air from the air pump to the canister for assuring a desired purge flow rate during each engine operation.