According to the reports of "The Club of Rome", the explosion of population, exhaustion of natural resources and the increase of the environmental pollution lead us to the "overshoot" and the succesive collapse of the modern world system. In order to prevent such a result, "population control" is the only positive-concrete way that man can take. In the entrance examination of the Faculty of Literature, Keio University in 1981, after reading some articles by a zoologist, examinees were asked to write down their own opinions about "population problems and the preservation of the species". We could get about 8,000 answer sheets. Attempts were made to investigate the overall trend of opinions concerning the problems of population. We pigeonholed 2,959 random-sampled answers (male: 1,699, female: 1,260) using the KJ Method which is a version of the Content Analysis. The major findings were as follows; 1) 84% of all opinions showed a quite optimistic expectation. 2) 62% distinctly expressed the need for positive means. 3) Only 30%-plus expressed the concrete-realistic means. 4) It is worth while noticing that 15%-plus expressed the need for birth control and population control, whereas more than 10% expressed opposition to them. 5) No sex difference in the trend of opinions was found.