This survey was carried out in order to find out population density of aphid at the alpine area. Thetraps were set from May 1 to October 31 in 1973. The summarized results are as follows; 1. About 37 species of aphids were trapped, including 4 species of potatao virus vectors. 2. Of these, dominant species are Aphis gossypii Koch, Aphis lerodendri Matsumura, and Lipahis erysimi Kaltenbaeh. The $67\%$ of 3, dominant species consisted of the trapped total aphids. 3. The potato virus vectors are Myzus persicae Sulzer, Aulacorhum solani Kaltenbach, Lipaphis erysimi Kaltenbaeh and Aphis gossypii Glover. 4. Tile number of aphids and vectors at the alpine area is considerably lower than that at the level land. 5. The peak of the flying aphid occurrence is shown in the latter part of September.