A drive unit for dish washing machines includes a flow channel housing, a filter housing and an arm holder, which are thermally fused to one another to form an integral unit. Consequently, assembly of the drive unit is simplified, leakage of wash water is prevented, and pumping performance is increased. Also, the flow channel housing, the filter housing and the arm holder are concurrently fixed to a pump housing of the drive unit by fixing members. Consequently, the assembly process of the drive unit is simplified, and the coupling force between the components of the drive unit is increased.