A thermoactuator easily installed in an object without compromising the operating characteristics of the thermo-element has an element case, containing wax that expands and contracts with changes in temperature; a supporting portion attached at one end to the element case by crimping, slidably supporting a shaft at another end; a cylindrical casing having an opening in one end, at least a portion of the supporting portion pressed through the opening in the one end of the cylindrical casing; and a flange expanding outward from the one end of the cylindrical casing, in which through-holes are formed for mounting the thermoactuator to an object to which the thermoactuator is to be attached. The element case is supported by one end of the supporting portion housed within the object to which the thermoactuator is to be attached and the casing is mounted on the object via the flange.