Effects of SbI3 addition to CH3NH3PbI3 precursor solutions on the photovoltaic properties were investigated. TiO2/CH3NH3Pb1-xSbxI3-based photovoltaic devices were fabricated in air, and formation of a perovskite-type structure was confirmed by X-ray diffraction. The conversion efficiencies were improved by adding a small amount of Sb, and formation of PbI2 was suppressed by the Sb addition.