[Object]An introducer assembly composed of an introducer sheath and a dilator which has been previously integrated with each other is provided. It permits the hemostatic valve to exhibit its hemostatic function over a long period of time without adversely affecting the inherent function of the dilator tube.[Solving Means]A introducer assembly has a dilator tube (50) passing through a passage (41) of a hemostatic valve (40) and it also has an introducer sheath (11) and a dilator (13) previously integrated with each other. The introducer assembly has a deforming member (90) arranged between the hemostatic valve and a cap (12). As the cap is pushed toward the proximal end surface of a sheath hub (30) for engagement with the sheath hub, the cap presses the hemostatic valve and applies a compressive force to the hemostatic valve in such a direction as to close the passage.
