Method of joining sheet member and sheet joined body

A method of joining a first sheet member and a second sheet member together, which includes

• forming an end face of the first sheet member and an end face of the second sheet member by overlapping the first sheet member and the second sheet member and cutting a given position of an overlapping area, wherein the first sheet member has an elongated band shape having a thickness in the range of 1 μm to 2 mm and is drawn out from a roll, and the second sheet member has an elongated band shape having a thickness in the range of 1 μm to 2 mm and is drawn out from a roll,
• bringing the end face of the first sheet member into abutment with the end face of the second sheet member to provide an abutted portion,
• heating the abutted portion via a heating medium to thermal-fusion-bond the end faces with each other, and
• peeling off the heating medium from the first and second sheet members after the thermal-fusion bonding, wherein
• the heating medium is an interposing material that includes thermosetting polyimide, has a light absorbing agent coated on the surface of the interposing material, and has a film shape having a thickness in the range of 20 μm to 500 μm, in which the abutted portion is heated by laser irradiation via the interposing material.