Abstract: In a heater in which an electrically insulating material (4) including an oxide is filled between a heating element (2) made of metal including chromium and aluminum and a cover (3, 5, 6) for sealing the heating element (2), and in which a lead wire (7, 8) of the heating element (2) extends through a portion (5, 6) of an electrical insulator of the cover (3, 5, 6) in order to enable the heater to be used at temperatures higher than the prior art, an oxide film including aluminum oxide is formed on the surface of the heating element (2). The portion of the cover (3, 5, 6) excluding the portion (5, 6) serving as an electrical insulator is a metal pipe (3) that serves as a sheath and includes nickel and chromium, and an oxide film is formed on the surface of the metal pipe (3). Therefore, the heater can be used in dies for plastic forming or the like.

Abstract: In a heater in which an electrically insulating material (4) including an oxide is filled between a heating element (2) made of metal including chromium and aluminum and a cover (3, 5, 6) for sealing the heating element (2), and in which a lead wire (7, 8) of the heating element (2) extends through a portion (5, 6) of an electrical insulator of the cover (3, 5, 6) in order to enable the heater to be used at temperatures higher than the prior art, an oxide film including aluminum oxide is formed on the surface of the heating element (2). The portion of the cover (3, 5, 6) excluding the portion (5, 6) serving as an electrical insulator is a metal pipe (3) that serves as a sheath and includes nickel and chromium, and an oxide film is formed on the surface of the metal pipe (3). Therefore, the heater can be used in dies for plastic forming or the like.