The actuators driven with the thin wire of functional anisotropic Ti-Ni-Cu base shape memory alloy are shown. The wire has large two directional shape memory effect of approx. 5% tensile strain. The property of the wire makes it easy to design shape memory alloy actuators with its wide operational range of low stress and large strain. The wire also shows a stable linear variation of the electrical resistance of approx. 20%, corresponding to the length variation in the two directional shape memory effect. The electrical resistance variation consists of the constituent by the phase transformation and the constituent by the length variation and has no hysteresis almost. A technology of servo actuators named SmartServo® in witch the variation of the electrical resistance is used as a positioning sensor was developed. The positioning feedback from the wire is performed through the same conducting wire as its driving use. This is suitable for the application of micro machines and robots. A differential micro servo actuator device based on this method was developed. The actuator device can turn its operational arm 90 degree in the speed of 0.2s bilaterally. The servo actuator device is driven by a couple of thin wire witch is approx. 60µm in diameter at 40mm long. The weight of this actuator device is only 0.8g including all the electrical circuitry of measuring resistance, signal processing and electrical current passage heating.