There is disclosed a photovoltaic conversion device constructed using a p-type crystalline silicon substrate 404 doped with boron, which comprises a bulk substrate region 404, regions other than the bulk substrate region including an n-type region 403a joining to a light receiving surface of the bulk surface region, a BSF region 405 joining to a back surface of the bulk surface region, wherein with regions other than the bulk substrate region 404 being removed, when a minority carrier diffusion length of the bulk substrate region 404 is measured from the light receiving surface of the bulk surface region, 0.5