To provide a tube and a medical light guide that can accurately grasp a position of a diffusion portion of light and can reduce friction.SOLUTION: A tube 20 according to one embodiment comprises: a transparent part 21 that transmits light having a wavelength equal to or longer than 600nm and equal to or shorter than 700nm； and an opaque part 22 that does not transmit light having a wavelength equal to or longer than 600nm and equal to or shorter than 700nm. The transparent part 21 and the opaque part 22 communicate with each other. An internal space 21a of the transparent part 21 and an internal space 22a of the opaque part 22 communicate with each other. The opaque part 22 has an aperture at a side of the transparent part 21. An opaque part 22's side opposite to the transparent part 21 is sealed. The transparent part 21 has an inner diameter into which a marker 12 fixed to an optical fiber 11 can be insert. The opaque part 22 has a portion with which the marker 12 comes into contact, the portion having an inner diameter smaller than the inner diameter of the transparent part 21.SELECTED DRAWING: Figure 4【課題】光の拡散部分の位置を正確に把握することができると共に、摩擦を低減することができるチューブ及び医療ライトガイドを提供する。【解決手段】一実施形態に係るチューブ２０は、波長が６００ｎｍ以上且つ７００ｎｍ以下の光を透過する透明部２１と、波長が６００ｎｍ以上且つ７００ｎｍ以下の光を透過しない不透明部２２と、を備え、透明部２１及び不透明部２２は、互いに連設し、透明部２１の内部空間２１ａ及び不透明部２２の内部空間２２ａは、互いに連通しており、不透明部２２の透明部２１側は開口しており、不透明部２２の透明部２１との反対側は封止されており、透明部２１は、光ファイバ１１に固定されたマーカ１２を挿入可能な内径を有し、不透明部２２は、マーカ１２が当接する部分であって透明部２１の内径よりも内径が小さい部分を有する。【選択図】図４
