To provide a method for molding a molded article, capable of equalizing a cross-sectional surface shape and capable of enhancing sealability, and a bonded molded article.

A pair of dies 1 consisting of a die 11 having a cutting blade 111 and a die having a blade receiving part 121. Molded articles 21 and 22 are arranged in the dies 11 and 12 and a sheet material 3 is arranged between the dies 11 and 12. Then, the dies 11 and 12 are relatively moved not only to cut the sheet material 3 but also to bond the opening end part 212 of the molded article 21 and the opening end art 222 of the molded article 22. Before bonding, a sheet hole 31 for allowing the hollow part 211 of the molded article 21 to communicate with the hollow part 221 of the molded article 22 is preliminarily bored in the sheet material 3.