Suicide among young people has become a serious social problem and is studied by many people. However research using statistics of suicide lags behind. The purpose of this article is to examine the relationship between the level of social development and the tendency of suicide among adolescents. To determine the value of a for each country investigated, a suicide rate of adolescents (15〜24 years old) is divided by that of the whole age group and then multiplied by 100. Then the values of a are compared on an international level and their changes are studied for the past seventeen years (1960〜1976). The following results are obtained. (1) In developing countries in Central America, South America, Southeast Asia, etc., the values of a are constantly high, exceeding 100 in many of them. Adolescents in developing countries which have many contradictions within their social structure suffer the most disadvantages. Therefore their ratio tends to be high. (2) The values of a are constantly low in developed countries mostly in Europe. (3) In some of the countries which have achieved social changes toward developed countries during the past seventeen years, the values of a have been on the decrease. Japan is a typical example. (4) In some developed countries, the values of a are on the increase (U. S. A., Canada, etc.). In these countries, the number of suicides as one of the "illness among adolescents in moratorium" might be large. This article investigates whether suicide tends to concentrate on adolescents or not in various countries by calculating the values of α. In the countries which have achieved social changes toward developed countries, the values of α have been on the decrease, but in the most developed countries, the values of α have been on the increase.