To attempt an improved productivity by making it possible to make continuously and reliably cooking materials put into an edible oil toward the lower-stream direction of an oil tank.

In the frame 3 arranged inside an oil tank 2, throw-in conveyor 6, the upper conveyor 7, lower conveyor 8 and a heater are installed. The throw-in conveyor 6 installed at the end of the upper-stream side of the oil tank 2 is arranged so as for the moving surface formed by a moving member to extend downward obliquely in front from a slightly higher position from the oil surface OL and for the leading end of the moving surface to be brought into close contact with the base end of the lower conveyor 8 located downward of the upper conveyor 7. Furthermore, the moving surface is formed in a flat shape by an endless belting having thermal resistance, nonstick property, low friction coefficient and high chemical resistance. As a result, cooking materials are hard to stick to the moving surface.