This paper presents a study on the research conducted by Jacques Copeau with expressionless mask. In the late nineteenth and early twentieth centuries, the actor was subordinate to the dramaturgical text. From this, questions emerge about theater and servitude to the dramatic text. In this context of questioning and changing theater arises the figure of Jacques Copeau - which at first does not intend to revolutionize theatrical language, just want to have actors who, besides knowing how to recite texts, can go further: that could speak with voice, body and soul. In his search for a new actor in the early twentieth century, Copeau used, among other pedagogical tools, the mask as a pillar of his pedagogy to create and educate a new actor, finding that the actor carrying this opens to emptyness and capacity of waiting, allowing himself to listen and then act, and act honestly, economically.