Dissatisfied with the basic concepts in the definition of vocational guidance, which NVGA approved and adopted in 1937, Donald E. Super studied that problem for more than fifteen years. We find the results of his research in his books and papers, in which the development of his concepts in vocational guidance can be followed. Inquiring into the problem "What is vocational guidance ?", Super thought of several new concepts, such as vocational adjustment, self-concept, personal counseling, career pattern, vocational development, and vocational maturity. Among them, his main concepts are vocational adjustment and vocational development which seem to make two important supports in his whole idea. Of the two, the concept of adjustment was studied first, whereas that of development was put on later. My comments on Super's concepts in vocational guidance and their development are as follows : (1) We should appreciate Super's laborious 'inquiry into the preceding concepts in vocational guidance and his great effort in the amendment and the development of them.(2) But I have two questions at present. First, Super redefined vocational guidance as the process of helping a person form and develop his self-concept. But is it not difficult for vocational guidance in any situation to actually render such assistance for development ? For example, while it is possible in school, is it not very difficult in the employment office ? Second, though the career pattern study is to be followed continually for a long time after graduation, how much does it contribute to those' who are still in school ? Is it not more important to catch the transition of the dimensions while they are attending school and to observe the patterns of such. transition ? (3) There has been no remarkable response on the' side of the scholars in the United States of America to Super's theories, which, on the contrary, have called forth some noticeable echoes among Japanese scholars. Super's redefinition has often been quoted by the researchers and a new definition is proposed, after Super's main concepts. (4) We have much interest in Super's emphasis in, the necessity to promote the study of the developmental psychology. After the discussion in the section of vocational guidance at the convention of the Japan Psychological Association held last July, it was resolved that we should carry on the study in vocational development of the adolescent in cooperation with each other.