PROBLEM TO BE SOLVED: To control an adhesive poured into between a protective cover and a sleeve member to be an appropriate amount.SOLUTION: An illumination optical system unit 26A comprises an optical fiber 37A, a phosphor 38, a ferrule 60 as a holding member for holding the phosphor 38 and the optical fiber 37A, a cylindrical sleeve member 61 for covering the outer periphery of the phosphor 38, and a protective cover 36 for sealing the distal end of the sleeve member 61. The ferrule 60 holds the phosphor 38 and is fitted in a fitting hole 71 of the sleeve member 61. The protective cover 36 is held by a receiving part 70 of the sleeve member 61. Since concentrically arranged circumferential grooves 75 are formed on a bottom surface 70b of the receiving part 70, when the adhesive 72 is poured into from a gap between the outer peripheral surface 36a of the protective cover 36 and the inner peripheral surface 70a of the receiving part 70, the amount of the adhesive 72 flowing from the outer side of the bottom surface 70b to the inner side is suppressed.
