Abstract: An injection drive apparatus for injection molding machines is revealed. Liquid material is fed into a mold smoothly by a material feeding screw of a material feeding mechanism. Then a reaction force is generated to push the material feeding screw when the material feeding hole is nearly full of the material. Thus the material feeding screw and the slide mechanism assembled therewith are pushed to move backward. Later the injection mechanism is driven by the slide mechanism to move and act on the drive screw. Thus the slide mechanism threaded with the drive screw is driven to push the material feeding screw moving forward and squeezing the material for injection molding. Therefore, the load of the motor is reduced dramatically and the yield rate of the products produced by injection molding is increased due to the two-stage action-feeding of the material and squeezing of the material for injection.