The peoples of the elementary school and junior high school with whom this investigation was made were the ones who the higher percentage of school myopia in 1971-1972. Compared to the whole country, the percentage of school myopia was about 3 times the average for the peoples of the elementary school and 1.5 for the peoples of the junior high school. The results of the investigation regarded the change in the power of seeing of the peoples after entering elementary school were as follows. There was a change in sixty percent of the peoples. It was evident that most of them gradually became worse in their seeing vision. The following are some of the reasons for becoming short-sighted. 1) The peoples of having too much food without a sufficient value of each nutritive elements (Cal., Protein, Fat, V.A, V.B1, V.B2, V.D) which should be ingested are apt to become short-sighted. 2) Most of the short-sighted peoples whose value for blood examination is less than the standard value. (blood examination; Hematocrit value, Hemoglobin concentration, Serum protein value) 3) Most of the short-sighted peoples have the some physical symtoms (commissural cheilitis, keratosis, abnormal patellar reflex). 4) There is no relation of cause and effect between relative weight and myopia. 5) It seems that there is not a certain relation of cause and effect between mothers' seeing vision and their peoples', but that they are gathered in their famillies which has the usually myopes. 6) Most of the peoples with good record at school are apt to have correct vision. 7) Most of the peoples who study at the room with low illuminance are apt to be short-sighted. But there is no relation of cause and effect between the illuminance of the room with a television set and myopia. 8) Most of the peoples who live in a room which there is little sun are apt to be short-sighted. 9) Most of the peoples who study for hours, or whose sleep is not enough are apt to be short-sighted. Considering the above items (No. 1-No. 9) in the view of statistics it is difficult to find a sufficient significance in them, but it is evident that they have made the reasons for many peoples' becoming short-sighted.