A method of manufacturing an integrated thin film solar battery module including a substrate, and a plurality of unit cells connected in series on the substrate, each of the unit cells having a first electrode layer, a semiconductor layer and a second electrode layer which are stacked one upon the other on the substrate. The method includes the steps of scribing the first electrode layer formed on the substrate, forming a semiconductor layer on the first electrode layer, scribing the semiconductor layer for each of the plurality of unit cells to form openings for connection to the first electrode layer, forming a second electrode layer on the semiconductor layer, scribing the second electrode layer and the semiconductor layer in the vicinity of the openings formed in the semiconductor layer, allowing an edge surface of the semiconductor layer to be exposed to the outside by removing residues of the second electrode layer and the semiconductor layer, and applying a heat treatment at 130° C. or higher after division of the second electrode layer and the semiconductor layer.