Provided is a pressure vessel having a weld portion structure of a plate material in which a plate receiving a pressure or a load is attached by welding to a wall surface member such as a shell or a head. In the pressure vessel, a stress concentration on the weld portion structure is alleviated and an increase in welding amount and plate thickness of the wall surface member are suppressed. The pressure vessel includes a weld structure portion in which an end of a bolster plate (22) attached so as to partition an inside of a container body and receiving a pressure or a load is attached by welding to a wall surface member (30) of the container body, the weld structure portion having at least two sections including a weld portion (40), i.e., shape displacement points of the weld portion (40) and a stepped portion (50).