PROBLEM TO BE SOLVED: To provide an endoscope that reliably prevents breakage of an optical fiber though having a low-cost and simple configuration without receiving restriction on arrangement inside an endoscope insertion part, and has a structure advantageous even to diameter reduction.SOLUTION: This endoscope includes: the optical fiber 55 inserted through the elongated insertion part 25 to be inserted into a test subject, and transmitting optical energy and a flexible protective tube 93 covering the periphery of the optical fiber 55 in at least a part of the insertion part 25 in the longitudinal direction. In the endoscope, the wall thickness of the tube wall of the protective tube 93 is larger than a minimum curvature radius causing the breakage of the optical fiber 55, and the tube outside diameter is smaller than the inside diameter of the insertion part 25. Thereby, even if bending the protective tube 93, the curvature radius occurring in the optical fiber 55 is always larger than the minimum curvature radius causing the breakage, so that the breakage does not occur.
