Bulk heterojunction organic thin-film solar cells utilizing soluble phthalocyanine derivatives, 1,4,8,11,15,18,22,25-octaalkylphthalocyanine (, , 7, 9, 10), were investigated. Two broad peaks existing in the external quantum efficiency spectra almost correspond to the Q-band and B-band of . The solar cell utilizing had the best photovoltaic properties as evidenced by open-circuit voltage, short-circuit current density, fill factor, and energy conversion efficiency. Almost the same photovoltaic properties were observed in the solar cells utilizing and . We discuss the photovoltaic properties by taking into consideration the crystal structure and electronic state of from the results of the absorbance spectra, X-ray diffraction measurement, and polarization microscope observation.