To provide a bag with a pouring port excellent in heat, pressure and water resistances, heat-sealing properties, resistance to thrust, resistance to pinhole formation, and lightproofness, further excellent in barrier properties for an oxygen gas, water vaport, etc., also capable of withstanding heat treatment and the like such as boiling treatment, further capable of reducing the quantity of refuse of containers and packaging materials and lowering the manufacturing cost of the bag, and excellent in packageability, shelf stability and the like for contents to be packed in the bag.

The bag is composed of a pouring port main body B consisting of a cylindrical mouth 1 and a boat-shaped bonded base portion 2 connected to the underside of the cylindrical mouth and a bag-like container main body fixed to the boat-shaped bonded base portion forming the pouring port main body. Further, the bag-like container main body is made of at least a laminated material in which a barrier layer provided with an inorganic oxide vapor- deposited film and a primer layer is laminated on one of faces of a base film and in which a lightproof layer provided with a metallized film and a heat- sealable resin layer are laminated on the other face of the base film in the order named.