BAG FOR PRESSURIZED SEALING, PACKAGE MADE UP THEREOF, AND PRODUCING METHOD FOR PACKAGE

PROBLEM TO BE SOLVED: To provide a bag for pressurized sealing and a package made up of such bag to which a fluid such as gas can be inducted smoothly from the outside through a nozzle only by installing a simple, film-like check valve without letting a momentary decrease of internal pressure happen on sealing up the bag after the induction of the fluid with the external appearance of the sealed-up package being fine with sealed-up matters such as tennis balls made visible from the outside and the initial internal pressure can be maintained within a permissible limit for a long period of time after being put on distribution while advantages in inexpensiveness in material and processing and easiness in disposal after use are ensured, and also to provide a method for producing such bag and package. SOLUTION: The bag 1 for pressurized sealing is in a structure wherein a film-like check valve 2 for induction of fluid is welded or made weldable to the inside of an opening of the bag 1. The film-like check valve 2 comprises an unsealed part serving as a passage 22 running from the upper end to the lower end and a sealed part 21 for forming the passage 22.