To provide a flat bag with a narrow outlet wherein an increase in cost due to formation of wastes in cut pieces of a film can be avoided, the narrow outlet can be formed without reserving a large dead space on an upper part of the bag, and two flat bags including the narrow outlet with a zipper or without a zipper wherein the zipper can be easily attached to the outlet without waste can be made at a time with their angle changed by 180 degrees, a manufacturing method thereof, and a package of the flat bag with the narrow outlet.

A front face 1 of the bag and a rear face 2 of the bag have side seals 5 applied on both side rims. An upper rim of the bag comprises a bent outline 6 symmetrical with respect to a middle point 6a of a length, forming the narrow outlet 7 and a shoulder 8. A top seal 10 is applied on an upper rim of the bag. A single line of a zipper strip 9 is provided at a height aligning with the middle point, and a lower end of the bag forms an opening 16.