A non-explosive separation device using a screw jack mechanism is designed, fabricated and tested for a small satellite. In order to activate the proposed device with a small amount of torque, we employ a double actuation mechanism which is initially triggered by a piezo actuator and finally activated by a spiral spring. Through theoretical analysis and experimentation, the specifications of the spiral spring and piezo actuator to activate the separation device are determined. Owing to the novel design of the mechanism, it can be activated within 0.65 sec under 100 $kg_f$ with 0.45 $kg_f$-cm of torque. Since screw jack mechanisms have commonly been used to upload heavy mass, and have self-locking capabilities under high load, a screw jack is also employed for the proposed separation device. Therefore, it can tolerate launching vibration as well as a thermal vacuum test without coming unfastened. The shock level is limited to 12 G, which is appropriate for a small satellite.