A metal forming system comprising an electrical heater, capable of conducting processes at elevated temperatures, was developed to perform micro backward extrusion processes of SUS 304 stainless steel. Two punches with diameters of 1.6 mm and 1.8 mm were used to extrude the billets inside the die with an inner diameter of 2 mm. All processes were lubricated with water-based graphite and conducted under isothermal conditions at 400 °C. The results show that the developed extrusion system can be used to produce the stainless steel components with a micro cup-shaped profile. Moreover, the variation in the rim height of the cups produced by the 1.8 mm diameter punch is greater than the one by the 1.6 mm diameter punch. The results show that a decrease in the clearance between the punch and die could lead to an increase in the inhomogeneity of material flow in the micro backward extrusion processes.