An insertion portion 31 having an illuminating unit 34 and the imaging unit 33 to the tip 32, inserted through the inside of the insertion section 31, the endoscope 1 illumination section illuminating light from the light source device 24 connected to the base end has a fiber 10 made of glass is provided to guide light up to 34, the aperture ratio, the light guide 13 is 0.46 to 0.90, not including lead light guide 13, X-ray of 2.5Gy light intensity of 380nm~750nm of X-ray resistance test after performing the recovery process to 600 minutes guiding the light of 64 lumens / mm 2 after irradiation is more than 67% of the light intensity of the X-ray resistance test before, and, ( blue light intensity ratio, which is the cumulative amount of light) of the integrated light intensity / 470nm~580nm of 380nm~470nm is 60% or more of the blue light intensity ratio of the X-ray resistance test before.内視鏡1は先端部32に撮像部33および照明部34を有する挿入部31と、挿入部31の内部を挿通し、基端部側に接続される光源装置24からの照明光を照明部34まで導光する、開口率が0.46~0.90であるライトガイド13と、を具備し、ライトガイド13が鉛を含まないガラスからなるファイバ10を有し、2.5GyのX線照射後に64ルーメン/mm2の光を600分導光する回復処理を行うX線耐性試験後の380nm~750nmの光量が前記X線耐性試験前の前記光量の67%以上であり、かつ、(380nm~470nmの積算光量/470nm~580nmの積算光量)である青色光量比が、前記X線耐性試験前の前記青色光量比の60%以上である。
