A suction apparatus of a cleaner includes: a suction motor inserted in a cleaner body and generating a suction force; a filter for collecting dust or filth sucked by a suction force generated for the suction motor; a suction head connected to the filter by a suction pipe and sucking dust and filth on the floor by the suction force generated from the suction motor; and an auxiliary suction unit installed at the opposite side of a side where the suction pipe of the suction head is connected. A cleaning performance is enhanced by compensating a suction force at a portion where the suction force is relatively weak.