A packaging bag having a steam venting function capable of releasing pressure inside a package even when heating cooking is performed by a microwave oven and preventing the inside of the bag from being contaminated and the package using the packaging bag. The packaging bag 1 comprises two pieces of front and back main body films 2 and 3 having sealant layers 2s and 3s which are opposed to each other with the sealant layers facing inward, side seal parts 5, and a bottom seal part 4. The front body film 2 is folded in the vicinity of the bottom seal part 4 throughout the entire width of the bag and parallel with the bottom seal part to form a fold-in part 8. A steam venting port 11 is formed in the fold-in part 8, and an easily peelable tape 12 covering the steam venting port 11 is disposed on the inside of the fold-in part 8 throughout the width of the bag and parallel with the fold-in part8, and then heat-sealed.