Pressure vessel

Disclosed is a pressure vessel including a boss extension portion having a cylindrical shape in which a through hole is formed at a central part to pass therethrough and a boss flange portion formed below the boss extension portion and integrally expanding outward in a radial direction along a circumferential direction in which the through hole extends in a vertical direction inward in the radial direction, a liner portion having a container shape in which an accommodation space configured to communicate with the through hole is formed to accommodate a fluid therein while a top is insertion-injection molded and seal-coupled along a bottom surface of the boss flange portion, and a sealing portion seal-coupled to a boundary area between a bottom of the boss flange portion and a top of the liner portion to block a leakage of the fluid accommodated in the accommodation space.