The length of an optical fiber from a portion aligned with the rear end of an insertion needle to a fixing portion is a length obtained by adding a predetermined extra length to a linear distance between the rear end of the insertion needle in a case where the insertion needle is located at a protruding position (insertion position) and an optical fiber fixing position of a grip portion. There is provided a fiber feeding adjustment mechanism that suspends the optical fiber with a first suspension portion and a second suspension portion so as to make a detour in a state in which there is no slack, and changes the detour length continuously according to the movement of the insertion needle in a case where the insertion needle moves between the retracted position and the protruding position, thereby maintaining a state in which the optical fiber is suspended without slack.
