Insertion device and photoacoustic measurement apparatus

An insertion device, comprising:

• an insertion needle that is inserted into a subject from a distal end;
• a grip portion that holds the insertion needle so as to be movable in an axis direction of the insertion needle;
• a needle injection unit for injecting the insertion needle from a retracted position to a protruding position away from the retracted position toward a distal end side of the insertion needle by a predetermined injection distance;
• and
• an optical fiber that is disposed in the insertion needle to guide light from a rear end of the insertion needle,
• wherein the optical fiber is fixed to the grip portion at a fixing portion that is separated from the rear end of the insertion needle to the other end side of the optical fiber, and
• a fiber feeding adjustment mechanism is provided that suspends the optical fiber between the rear end of the insertion needle and the fixing portion in the grip portion so as to make a detour in a state in which there is no slack and changes a detour length continuously according to 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.