PURPOSE: To provide the speed control method and its device for an injection molding machine for carrying out multi-stage control optimum for a molded product by selecting the movement speed of a movable component through a plurality of servo valve control bodies.

CONSTITUTION: The injection speed set value is set to a movement speed setting device 13 when a fluid is fed to a first port side 2A of an injection cylinder 2 and a screw 1 connected with the injection cylinder 2 is moved forward, which means the injection of molten resin. Servo valve amplifiers 7 and 11 and servo valves 6 and 10 optimum to the speed set value is selected and changed over automatically by a controller 9. Thus the value of flow rate control corresponding to the molding condition of a molded product can be varied delicately along the lapse of time of the molding process, and the molding of various different shapes, wall thickness and the like can be carried out.