The present invention relates to an apparatus and method for decreasing drag force by controlling turbulent flow in a hull surface of a ship. The method and apparatus according to the present invention are directed to sucking and ejecting the fluid flowing along a hull surface of a ship, varying the turbulent field of the turbulent flow, controlling the ejection angle with respect to the hull surface and decreasing the friction resistance by providing a pipe housing which is installed in a hull surface of a ship and includes a plurality of slits, a flexible air pipe which is installed in the interior of the pipe housing and performs contracting and expanding operation based on air pumping operation, and a pump which is installed in the hull for contracting and expanding the air pipe and providing air to the air pipe. The pipe housing including the flexible air pipe is installed inside or outside the hull surface for thereby contracting or expanding the air pipe using the pump, so that the fluid from the slits is sucked and ejected to vary the turbulent field of the turbulent flow formed on the hull surface and decreasing the friction resistance.