Properties of organic thin photovoltaic cells using copper phthalocyanine (CuPc) with different purities are studied. When we change purity of CuPc, only open-circuit voltage (V-OC) increases as CuPc material purity increases while short-circuit current show a same value. Decrease in VOC of cell using low-purity CuPc is maybe caused by impurities that are taken in CuPc layer. We show the model to explain this phenomenon and examine propriety of it.