PURPOSE: To open or close or valve by utilizing a bend due to a difference between thermal expansion coefficients by a method wherein the heat pipe is constituted to accommodate a capillarity wick and an operating fluid within a tubular enclosed vessel consisting of different two kinds of metals or alloys which are connected in the axial direction thereof.

CONSTITUTION: The tubular enclosed vessel 2 is made by connecting different two kinds of metals or alloys in the axial direction of the vessel 2 in order to utilize positively the difference between the thermal expansion coefficients of two kinds of metals or alloys. The wall 1 of the heat pipe is constituted by connecting two kinds of metals or alloys which are having different thermal expansion coefficients in the axial direction of the pipe, therefore, when heat is flowed into one end of the heat pipe, the pipe is bent to the side of the metal having high thermal expansion coefficient.