An object is to increase conversion efficiency of a photoelectric conversion device without increase in the manufacturing steps. The photoelectric conversion device includes a first semiconductor layer formed using a single crystal semiconductor having one conductivity type which is formed over a supporting substrate, a buffer layer including a single crystal region and an amorphous region, a second semiconductor layer which includes a single crystal region and an amorphous region and is provided over the buffer layer, and a third semiconductor layer having a conductivity type opposite to the one conductivity type, which is provided over the second semiconductor layer. A proportion of the single crystal region is higher than that of the amorphous region on the first semiconductor layer side in the second semiconductor layer, and the proportion of the amorphous region is higher than that of the single crystal region on the third semiconductor layer side.