Photoirradiation effects of a polypyridine, PPy/poly(2-methoxy-5-dodecyloxy-p-phenylene vinylene), MDOPPV heterostructure photoelectric conversion device have been investigated. The photovoltaic characteristics of the heterostructure photoelectric conversion device are considerably improved from those in single-layer photoelectric conversion devices. Quenching of photoluminescence both in the PPy layer film and in the MDOPPV layer film has also been observed in the PPy/MDOPPV heterostructure film. The observed photoirradiation effects of the heterostructure device indicate that a photo-induced charge transfer occurs between PPy and MDOPPV. However, the photo-induced charge transfer between these polymers cannot be explained by the bulk electronic energy states of the polymers. A possible mechanism, which takes modulation of electronic energy states at the interface due to a local lattice distortion into account, has been proposed.