NOVELTY - A laminated structure of buffer layer and conductive layer is provided on the photoelectric conversion semiconductor layer of a flexible substrate (A), to obtain a photoelectric conversion element. The semiconductor layer surface is immersed in a surface treatment liquid and water-washed. The substrate is adhered to a drum (3) of chemical bath deposition (CBD) apparatus (1). A portion of drum contacting with the substrate is immersed in CBD reaction liquid (4) and the buffer layer is formed.    USE - Manufacture of photoelectric conversion element e.g. solar cell.    ADVANTAGE - The method enables formation of buffer layer without elution of component from substrate, even when component which dissolves in CBD reaction liquid is contained. The method provides photoelectric conversion element having excellent photoelectric conversion efficiency.    DETAILED DESCRIPTION - A laminated structure of a buffer layer and a translucent conductive layer is provided on the photoelectric conversion semiconductor layer of a flexible substrate having a lower electrode and a photoelectric conversion semiconductor layer, to obtain a photoelectric conversion element. The photoelectric conversion semiconductor layer surface is immersed in a surface treatment liquid. The surface-treated substrate is water-washed and water adhered to the substrate is removed. The substrate is adhered to a drum of chemical bath deposition (CBD) apparatus and the drum is immersed in a reaction tank (5) filled with CBD reaction liquid. The portion in which the edge portions of substrate and the drums do not contact is overlapped by a protection component (6) and protected from the CBD reaction liquid. A portion of drum contacting with the support is immersed in the CBD reaction liquid thermally regulated in the film-forming temperature, and a buffer layer is formed as a film on the photoelectric conversion semiconductor layer. The substrate is then washed with a cleaning liquid and the cleaning liquid adhered to the substrate is removed, to obtain a photoelectric conversion element.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic perspective view of the laminate of photoelectric conversion element.    CBD apparatus (1)    Drum (3)    CBD reaction liquid (4)    Reaction tank (5)    Protection component (6)    Flexible substrate (A)