A belt type continuous casting machine having a container for accommodating molten steel therein, a nozzle for supplying the molten steel from the container, a belt mold having a pair of metal belts and a pair of side members, and a cooling pad positioned adjacent to the back surface of the metal belt for forming a gap acting as a water film portion therebetween. The cooling pad is provided with a plurality of inlet ports and outlet ports for enabling a flow of cooling water into the water film portion therethrough. The diameters of these ports and the vertical distance between the inlet port and the adjacent outlet port are varied for controlling fluid pressure in the water film portion in correspondence with an external load acting on the metal belt. By securing a desired water film thickness deformation of the belt mold is prevented, and a flat cast slab with a good surface is obtained.