A water treatment apparatus and a water treatment method using the same are provided. The water treatment apparatus includes a cohesive agent input device configured to input a cohesive agent to raw water, a membrane filtering device, a raw water pump configured to transfer raw water including the cohesive agent therein to the membrane filtering device, a water supply flow path connecting a discharge side of the raw water pump to the inlet of the membrane filtering device, a circulation flow path connecting the raw water discharge opening of the membrane filtering device to the water supply flow path and a circulation pump provided in the circulation flow path to transfer discharged raw water to the water supply flow path.