The writer had published "Study on Rainfall Measurement in Mountain Area: (1) Selection of the Correct Raingauge," in which the vector raingauge" had been proved not to catch the correct rainfall. Those results were got from March 1968 to October 1971 in Kyushu, Japan. For further study, two experiments were conducted in Huei-Sun Experimental Forest, Chung-Hsing University and in Pin-Zau-Nair, Alisan Mountain. Three sets of vector raingauges (each set contained E, W, S, N directions) were set along the contour line on the slope. According to the rainfall data, the results showed great variation or great range in the same direction. Therefore, the vector raingauge did not reveal the rainfall direction correctly. In this paper the writer also proved the vector raingauge seemed to be uncorrect in rainfall measurement.