A method of manufacturing a fuel tank includes: an introducing process in which a molten resin sheet formed with a tank body is introduced in a forming mold; a shaping process in which a movable member abuts against the molten resin sheet to form a molten resin projection projected in a thickness direction of the molten resin sheet; an arranging process in which the molten resin projection is inserted in an attachment hole provided in an attachment part, and the attachment part is arranged on the molten resin sheet; and a machining process in which the molten resin projection is pressurized by a pressurizing member, so as to bulge out a portion of the molten resin projection to an outer peripheral side.

The present invention provides a container forming apparatus, a container forming method, a container, and an instant food packaging method using the container. The container forming apparatus, which is a container forming apparatus for forming a container by thermoforming, comprises: a bottom forming part for forming the bottom portion of the container; a side forming part extending upwardly inclined from the bottom forming part and configured to form a part of the side portion of the container; a first form part configured to rise upward and pressurize the container to separate and take out the formed container; and a second form part disposed outside the first form part and configured to form the remaining parts of the container except the part of the side portion.