Bulk heterojunction organic thin-film solar cells utilizing soluble phthalocyanine derivatives, 1,4,8,11,15,18,22,25-octaalkylphthalocyanine (CnPcH2, n = 6, 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 CnPcH2. The solar cell utilizing C6PcH2 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 C9PcH2 and C10PcH2. We discuss the photovoltaic properties by taking into consideration the crystal structure and electronic state of CnPcH2 from the results of the absorbance spectra, X-ray diffraction measurement, and polarization microscope observation.