PURPOSE: To improve an operability in bending an endoscope by spreading wires made of a shape memory alloy along certain parts of outer peripheries of a couple of flanges connected flexibly by a joint and by making those wires contracted by heating.

CONSTITUTION: A couple of flanges 22, 23, which are set opposite to each other with a specified spacing, are connected with each other by a joint 21 restorably and flexibly. wires 28 made of a shape memory alloy, which is contracted by heating due to a shape memory effect, are spread along certain parts of outer peripheries of the flanges 22, 23. The wires 28 is selectively heated by a device consisting of lead wires 36, 37a, 37b, a changeover switch 38, a power source 39 for heating, a variable resistor 40, etc. A motive force for bending is increased by an action due to the shape memory effect, a large bend angle is obtained and also an operability in bending an endoscope is improved as a result.