A method for manufacturing a thin film photoelectric conversion module comprising the steps of: (A) forming a plurality of divided strings by dividing a string, in which thin film photoelectric conversion elements provided by sequentially laminating a first electrode layer, a photoelectric conversion layer and a second electrode layer on the surface of an insulating substrate are electrically connected in series, into a plurality of strings by dividing grooves, electrically insulating and separating the first electrode layer and the second electrode layer one from the other and extending in a serial connection direction; and (B) performing reverse biasing by applying a reverse bias voltage to each of thin film photoelectric conversion elements of the divided string.