The authors have proposed a new MPPT (Maximum Power Point Tracking) control with I-V characteristics scanning for a PV generation system. This proposed method has the extremely high MPPT efficiency due to scanning the I-V characteristics periodically. This paper investigates the characteristic in the partial shadow of this MPPT method. From the experimental results，it is clarified that even if a partial shadow is occurred，this MPPT m ethod can accurately detect the maximum power point. In the partial shadow by stone pillars，the proposed method yielded 158 Wh over the length of the experiment while the conventional method yielded only 110 Wh,an increase of approximately 44%.