To provide an introducer sheath provided with a side hole on a specified position so as to measure a blood pressure electrocardiogram without enlarging a sheath outer diameter.

This introducer sheath 1 is composed of a sheath 13 provided with a hollow structure continuing from a base end part to a tip part and a hub 14 attached to the base end part of the sheath 13, the sheath 13 is provided with the straight part 22 of a main body and a tapered part 15 at a tip, at least one side hole 16 is provided on the side wall of the sheath 13 and the side hole 16 is provided on the straight part 22.