To obtain good-quality paper bags which are free from such a trouble that the part attached by an adhesive is not easily released, even when a synthetic paper is used as a material sheet.

This sheet bag making machine is structured of a sheet supply part 1 which supplies material sheets one by one, a barrel forming part 3 which forms the sheets into flat and barrel-like bodies with both gusseted sides while running the material sheets supplied by the part 1 and an angular bottom forming part 4 which forms a square bottom face at one end opening of the barrel-like body obtained by the barrel forming part 3. In the machine, a pasting part 3A for bonding both edges of the material sheet is provided at the barrel forming part 3. Especially, at the pasting part 3A, a nozzle 5 which discharges an adhesive to one edge of the material sheet and an ascending/descending contactor 12 which spreads the adhesive discharged from the nozzle 5 like a belt along one edge of the material sheet are provided. Thus, both edges of the sheet can be firmly bonded instantaneously.