A method for manufacturing a fusion-bonded sheet article that includes sealed edge sections made by fusion-bonding edge sections of a plurality of sheets in a state where the sheets' edge sections are superposed, wherein: at least one sheet of the plurality of sheets includes a resin material, the manufacturing method comprises a step of forming the sealed edge sections by making one surface of a belt-shaped sheet laminate in which the plurality of sheets are laminated abut against a support member that has a light passage section through which a laser beam can pass, and irradiating, from the support member side via the light passage section, the belt-shaped sheet laminate which is in a pressurized state with a laser beam having a wavelength that is absorbed by the sheets constituting the sheet laminate and that causes the sheets to generate heat, and thus cutting and separating the belt-shaped sheet laminate and, simultaneously, fusion-bonding cut edge sections created, by the cutting/separation, in the plurality of sheets which are in the pressurized state, the light passage section is a slit-shaped opening that penetrates the support member in its thickness direction, a protruding section is formed in a vicinity of the opening on an outer surface of the support member where the sheet laminate is arranged, the protruding section protruding more toward the sheet laminate arranged on the outer surface than peripheral sections of the opening, a plurality of the fusion-bonded sheet articles are manufactured continuously, and the step of forming the sealed edge sections includes an anterior holding step of arranging the sheet laminate on the outer surface of the support member that travels in a predetermined direction, and holding the sheet laminate in a pressurized state on the outer surface of the support member, an irradiation step of irradiating the sheet laminate, which is held in the pressurized state on the outer surface of the support member, with the laser beam from an inner surface side of the support member via the light passage section, and thus cutting and separating the sheet laminate, and a posterior holding step of, after termination of the laser beam irradiation, holding the cut/separated sheet laminate on the outer surface of the support member while maintaining the pressurized state. at least one sheet of the plurality of sheets includes a resin material, the manufacturing method comprises a step of forming the sealed edge sections by making one surface of a belt-shaped sheet laminate in which the plurality of sheets are laminated abut against a support member that has a light passage section through which a laser beam can pass, and irradiating, from the support member side via the light passage section, the belt-shaped sheet laminate which is in a pressurized state with a laser beam having a wavelength that is absorbed by the sheets constituting the sheet laminate and that causes the sheets to generate heat, and thus cutting and separating the belt-shaped sheet laminate and, simultaneously, fusion-bonding cut edge sections created, by the cutting/separation, in the plurality of sheets which are in the pressurized state, the light passage section is a slit-shaped opening that penetrates the support member in its thickness direction, a protruding section is formed in a vicinity of the opening on an outer surface of the support member where the sheet laminate is arranged, the protruding section protruding more toward the sheet laminate arranged on the outer surface than peripheral sections of the opening, a plurality of the fusion-bonded sheet articles are manufactured continuously, and the step of forming the sealed edge sections includes an anterior holding step of arranging the sheet laminate on the outer surface of the support member that travels in a predetermined direction, and holding the sheet laminate in a pressurized state on the outer surface of the support member, an irradiation step of irradiating the sheet laminate, which is held in the pressurized state on the outer surface of the support member, with the laser beam from an inner surface side of the support member via the light passage section, and thus cutting and separating the sheet laminate, and an anterior holding step of arranging the sheet laminate on the outer surface of the support member that travels in a predetermined direction, and holding the sheet laminate in a pressurized state on the outer surface of the support member, an irradiation step of irradiating the sheet laminate, which is held in the pressurized state on the outer surface of the support member, with the laser beam from an inner surface side of the support member via the light passage section, and thus cutting and separating the sheet laminate, and a posterior holding step of, after termination of the laser beam irradiation, holding the cut/separated sheet laminate on the outer surface of the support member while maintaining the pressurized state.