Fatigue property of shape memory alloy TiNi in the form of thin film was investigated. The specimens with the thickness of 6 mm, 2 mm and 0.5 mm were fatigued in order to clarify the effect of the constraint of martensitic phase, which possesses higher fatigue crack propagation resistance than that of austenite. The results show that crack propagation rate was lower in the thin specimen. This is attributed the existence of higher hydrostatic pressure in the thick specimens. The hydrostatic pressure is considered to lower martensitic transformation. As a result, TiNi thin film actuator is expected to have superior fatigue property than the bulk samples. In order to evaluate the properties of the TiNi thin film actuator, the diaphragm was produced on Si/SiO_2 substrate. The heating and cooling process shows that the TiNi diaphragm moves in the substrate direction when constrained in the right way.