In an NiMnGa alloy represented by the chemical formula of Ni2+XMn1−X Ga, a composition ratio parameter X (mol) is selected within a range of 0.10≦X≦0.30. With this composition, the finish point of the reverse transformation of the martensitic transformation can be selected to a desired temperature within the range between −20° C. and 50° C., while the Curie point is also selected to a desired temperature within the range between 60° C. and 85° C. The alloy has the shape memory effect by the martensitic transformation and the reverse transformation. Furthermore, the alloy is induced with the reverse transformation by application of an external magnetic field at the martensite phase to exhibit the shape recovery.