An insertion device sets engage range which it prescribed in return power to the neutral position by elastic force of the spring and rotation resistance force by the slide power by elastic member for dial portion performing curving operation of a curving portion. The creation of a voice portal is supported by the invention. Each pedal mechanism is linked to a steel rope of a linking mechanism so that the pair of the pedal mechanisms can move back and forth against each other alternately along the non-parallel linear tracks. The oxide layer includes at least one element selected from the group consisting of Zn, In, Sn, and Cd, and at least one element selected from the group consisting of Fe, Co, and Ni. The second electrode located to the heating element is connected to ground, and the first electrode coacting with the second electrode is negatively polarized, a negative operating voltage being provided.