Robert Frank's works could be characterized by two periods. The first is the period of realistic pictures as ‘The Americans’ published in 1958. In the book, he, as a European immigrant, criticized the contradictory circumstances in America with the realistic view point. Especially he pointed out the State as the industrialized democratic society ignores the human personality and lords her people over. Such criticism could be done only by Robert Frank who had experienced two different cultures. The second is the period of complex pictures he has made after 1960. At first he had taken motion pictures and experienced the new expressions like multi view points and editing. The basis of the complex pictures was formed by such techniques. In the complex pictures, he represented the dual aspects of life as happiness and unhappiness that Robert Frank had experienced such severe sorrows of his daughter's death and divorce, etc. So he always set the scene of seashore with the sky and the sea in the picture which symbolize the dual aspects of life. The change in his works was caused by the change of his cognitive structure which was the result of his life experience and means the change from Realism to Modernism. In the conclusion, he accomplished two outstanding achievements with different view points and techniques.