This study is to rediscover the value of the dreams in psychotherapy, by examining the language of dream as a carrier of the unconsciousness. To do this, I have taken a look at relations between dream and the unconsciousness, and then searched how discourses of the unconsciousness is modified and extended, through the Lacan’s theory that linguistically reinterpreted Freudian psychoanalysis. The dreams are fantastic realization of oppressed desires, so they are distorted and transformed in the process of conscientization of unconsciousness. Freud stressed the content of dreams in symbolic system, while Lacan completely excluded the meanings of the dreams and focused on the structure of the dreams and unconsciousness. But in some ways, we can argue that Lacan succeeded and developed Freudian theory, by reestablishing linguistically key issues and expanding widely the concept of unconscious in psychoanalysis. Freud believed that the dreams must go through processes of condensation, displacement and distortion in the dreamwork, Lacan approached linguistically to this Freudian mechanism through the concept of metaphor and metonymy. Freud explained that the unconsciousness and preconsciousness have different languages, paid attention to linguistic properties and singularities of the unconsciousness. Lacan expanded such arguments and concluded that the unconsciousness is structured like a language. Although dreams may not tell us the whole story and picture of our desires, we can utilize Freud and Lacan’s works on dreams and desires as a task to properly intervene in the psyche of subjects who are divided and alienated in modern society.