The distal end of an insertion section of an endoscope is divided into a plurality of segments each including a pair of SMA coils which are arranged symmetrically with respect to an axis and memorize a close-winding shape. As the SMA coils recovers their memorized shape, the distal end of the insertion section is bent. The SMA coils are restored to the memorized shape when they are conductively heated by means of a current supply circuit. The current supply circuit comprises an input unit for inputting a target value of the bend angle for a leading segment, a sensor for detecting the distance of insertion of the insertion section, a detector circuit for detecting the bend angle of each segment, and means for controlling the amount of current supply so that the bend angle of the SMA coils agrees with a target angle. The inputted angle is set as the target angle for the leading segment, and the detected bend angle of each segment is set as the target angle for each succeeding segment. The set value is renewed each time the insertion distance of the insertion section attains a predetermined distance.