PURPOSE: To prevent insufficient heating or excessive heating by providing a heating means clamping and heating a pipe coupling in a heater heating the pipe coupling made of a shape memory alloy, and forcefully releasing the clamped pipe coupling when proper heating is detected.

CONSTITUTION: A heater is provided with arm sections 2a, 2b at the tips of a pair of handles 1a, 1b, and a pair of carbon electrodes 3a, 3b are provided at the tips of the arm sections 2a, 2b. The handles 1a, 1b are pivotally supported by a fulcrum member 4, and they are closed by the action of an opening/closing control device 6 against a spring 5. When two pipes are to be connected, a cylinder member made of a shape memory alloy is outwardly coupled with a connection portion, then the cylinder member is clamped by both electrodes 3a, 3b, the electrodes 3a, 3b are excited and heated, and the cylinder member is shrunk to the memory shape to connect the pipes. When the proper heating state is detected, the opening/closing control device 6 is made the free action state, and the electrodes 3a, 3b are separated by the spring 5.