In the pouch manufacturing method, a branched part (254) is formed by folding back at least one side part of a web-form body member (240) at a fold-back line running along the feeding direction of this body member. The body member (240) is guided by a guide so that the pass line length of a portion occupying an arbitrary position is substantially constant from the initiation of fold-back to the completion of fold-back; accordingly, a natural and favorable fold-back can be achieved without generating any slack or wrinkles in the web, so that pouches such as pouches having a branched part (254) can be manufactured with a favorable appearance and commercial properties.