This study is intended to examine Honore Daurnier's realism formativeness, review it in connection with socio-cultural conditions, analyze costume designs by a style of realism formativeness, in order to find the value. For the study, the procedure included the review of Daurnier's works and world, together with realism formativeness. Then, Daurnier's realism formativeness applied to costume designs were categorized and found the features of each style. Finally, it sought the implication of realism formativeness in costume designs. Honore Daumier, a realist of France in the 19th century, has been reputed that he pursues plain reality with a satire, uses all the conditions of humans as his object, and observes the vanity, desire, and foolishness of humans to represent his own expression techniques as cold as a stone. Realism formativeness is characterized by adherence to observing reality and engagement in reality, an effort to represent the world as it is as what we sense it without diluting or omitting it, nor any deception. The following terms can be used to describe the three styles of intentional recreation, satire on reality, and real existence; For intentional recreation in costume may be featured by the avant-garde, the pursuit of autonomy, reconstruction, rediscovery, recombination, reinterpretation, neutralized representation (reality ＋ the abstract), transformation, distortion, shock, and unexpectedness, etc. For satire on reality in costume, satirical criticism and mockery in a coexistence of time and space, dualism due to the combination of the exterior and the interior, reality reflecting the actual reality, and irony are those words. Real existence in costume may be described with objectivity, ordinariness, correctness of representing a theme, impersonality excluding subjectivity, clearness, certainness, and preciseness, etc.