[Problem] Provided is an introducer with which it is possible to easily distinguish an introducer provided with a sheath tube of which the wall thickness is reduced, from an introducer provided with a previous sheath tube of which the wall thickness is not reduced, and to easily recognize the relationship between the inner diameter and the outer diameter in regards to the sheath tube of which the wall thickness is reduced. [Solution] An introducer 10 includes an introducer sheath 20 which includes an elongated hollow sheath tube 21 and a sheath hub 22 which is provided at the proximal side of the sheath tube and provided with an insertion port 25a through which the dilator 30 is inserted. A first information piece 51 having an inner diameter dimension of the sheath tube as an index is shown on at least one of the sheath tube and the sheath hub. Furthermore, a second information piece 52 having an outer diameter dimension of the sheath tube as an index is shown on at least one of the sheath tube and the sheath hub.
