This study is an attempt to imvestigate the relationship between the mentally healthy personality and the accuracy of perception of self and others. On the 341 junior high school students, including boys and girls, the Kraepelin Psychodiagnostic Test was administered and these students were classified into A, B, C, D and E goups in proportion to degrees of normality and abnormality, depending on the interpretation of the curves obtained. On the same subjects, again, the anticipated marks for themselves and others in the term-end examination on a specific curriculum were made to be entered, which, then, were compared with their actually obtained marks, and the discrepancy between both was calculated. The following results were found : 1) The healthier the personality is, the less discrepancy exists between the anticipated and actual marks, and the more accurate is his understanding of real personality, whether of one's own or of other's. 2) Discrepancy between the anticipated and actual marks is slightly smaller with the male than female students. 3) Discrepancy is most prominent with the students of the first and the third grade years, and less apparent with the second year students. Also, as the school year abvances, the discrepancy between anticipation and reality grows bigger between both sexes. 4) The discrepancy between anticipation and reality related to one's self is smaller than that related to others. 5) The healthier personality is, the more likely he is to underevaluate himself and others rather than overevaluate. However, in common with all groups indicating varying degrees of normality, a strong tendency exists, which overevaluates when making anticipations about others. 6) The healthier the personality is, the less prominent is the contradiction between the attitude to one's self and to others.