NOVELTY - An adhesive sheet having adhesiveness at a preset temperature is attached on a front surface side of solar cell elements (10) on a semiconductor layer (11) above a substrate. The solar cell elements are peeled from substrate by producing a tensile stress between adhesive sheet and the substrate. The adhesive sheet is peeled from solar cell elements by heating adhesive sheet to a temperature making adhesive force of the adhesive sheet zero. A back surface protection film (21) is adhered on the back side of solar cell elements through a contact bonding layer (22).    USE - Manufacturing method of integrated thin film element. Uses include but are not limited to manufacture of solar cell element for manufacture of integrated single-crystal-thin-film silicon solar battery, light receiving element, light emitting element, LCD element, and integrated circuit (IC) element.    ADVANTAGE - The number of process steps is reduced by peeling adhesive sheet from the surface side of the solar cell element without applying a tensile stress. The yield and through-put during the manufacture of integrated thin film element are improved by forming the element isolation groove precisely and easily. The solar cell has high conversion efficiency and enables use of low energy indoor light. The bypass resistance for preventing damage of integrated solar cell is formed using a simple process. The etching groove is formed accurately within a short time by performing laser etching of only the semiconductor layer. The solar cell having low weight and flexibility is obtained by using a flexible back surface protection film.    DETAILED DESCRIPTION - A porous semiconductor layer is formed on the surface of a semiconductor substrate. A semiconductor layer (11) is formed on the porous semiconductor layer. Several solar cell elements (10) are formed on the semiconductor layer. An adhesive sheet having adhesiveness at a preset temperature is attached on the surface side of the solar cell elements. The solar cell elements are peeled from the substrate by producing a tensile stress between the adhesive sheet and the substrate. The adhesive sheet is peeled from the solar cell elements by heating the adhesive sheet to a temperature making adhesive force of the adhesive sheet zero. A back surface protection film (21) is adhered on the back side of the solar cell elements through a contact bonding layer (22).    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the solar cell manufacturing process.    Solar cell element (10)    Semiconductor layer (11)    Cathode (14)    Anode (15)    Element isolation groove (17)    Back surface protection film (21)    Contact bonding layer (22)