A fuel supply device for direct methanol fuel cells. The fuel supply device for direct methanol fuel cells includes a fuel tank to store a liquid fuel, a cavity plate to store the liquid fuel transferred from the fuel tank, a thin film type active pump welded on the bottom of the cavity plate to bring about a movement of the cavity plate, and a nozzle plate disposed on the cavity plate to eject the liquid fuel. Accordingly, it is possible to actively control a liquid fuel in a needed amount and supply it to a fuel cell in accordance with a use mode of an electronic device and effectively remove by-products of the fuel cell, thereby improving the efficiency of the fuel cell.