In this study, a new electro-magnetic proportional actuator composed of an armature and stator with multi convex teeth to control oil hydraulic valves was designed and examined. Each of the convex teeth forms a magnetic pole, and when multiple magnetic poles produce a force simultaneously, a large thrust force is generated in the actuator. The shape of the teeth was varied and influence on the thrust force was examined. As a result, the interval between the convex teeth could be reduced. A 10-step pole type actuator was designed, and its thrust force was estimated. When the dimensions of this actuator are 52mm height, 68mm width, by 102mm length, its thrust force is constant within 2mm of the armature stroke, producing about 300N at an electric power consumption of 15W, and it generates the thrust force in proportion to the coil current. The thrust force of this actuator is about 2.5 times as large as that of conventional proportional solenoids and linear motors of the same installation area to the valve body, length and power consumption.