Theatre enjoys the highest status in social relationships and this trait arises from two characteristics: the first one is that theatre is formed at the time and place of performance. Theatre is created in specific time on stage for the audience. The second one is direct presence of the audience which is the third basic element of theatre. Theatre is created through direct encounter of actors and audience. This two-sided relation forms the unique social relationship of the theatre. In traditional theatre plays, which are performed in public among ordinary people from different social cast, this sociological trait is clearer. In these plays, in which the most important aim is the relation with audience, the comedy version is performed in improvised base and tragic version is performed with improvised parts. These improvisations can propound the people's social views.Although there are valuable researches about Iranian traditional theatre, this type of theatre has rarely been researched from cultural and sociological point of view. The Bakhtin Carnival’s theory, which is assigned in sociological studies realm, is widely applied in critical literature but less applied in sociological analysis of theatre types. Bakhtin believes that ritual theatre consisting of arena and street theatre are forms of carnival. One of the characteristics of carnival setting is heteroglossia, in which different voices can be heard and one of its representations is laughter. Then having dialogue, participation, equality and freedom are the important functions of carnival. All of these contribute to its creation. In carnival, difference and casts disappear and everyone can utter his view freely. People experience another life with freedom in carnivals. In totalitarian governments, carnival is a resistance against hegemonic power. But sometimes the government resorts to carnival as a factor of trust. They use carnival consciousness or unconsciousness to decrease social and economic pressure on people. For searching carnival conditions, it should be defined through its signs in theatre. Dramatic signs of carnival consist of place sign, social sign, speech sign, behavior sign and conceptual sign. For finding these signs in traditional theatres of Nasrei period (Nasereddin Shah), a basic knowledge of this period is necessary. Nasereddin Shah’s period has been the longest and the most eventful period of Qajar dynasty. This period's social and political developments, which are contemporary with 19thcentury evolutions in Europe, make it a passage time from traditional to modern society.Nasereddin Shah was a dictator who liked reforms. He not only had no negative view about reforms but also considered them necessary and useful for the government and for improving the society. On the other hand, he was such voluptuary spending most of his time in leisure pursuits hence supporting theatres as a means of amusement. These theatres had three types: Ta`ziyeh, Shabih Mozhek and Dalghakbazi (clown play). Qajar's kings preserved the tradition of Ta`ziyeh extensively and raised it to a high status. Ta`ziyeh ceremonies among non-cast groups brings people close to each other and create a feeling of unity and common aim, which is promoting justice and battling against cruelty. There are some traces of carnival in Ta`ziyeh, such as participation and heteroglossia, creating a different life vis-à-vis formal life and non-existence of any distance between actors and audience. Along with Ta`ziyeh, there exist some other types of play which lack any mourning mood; rather, they amuse people and bring about happiness: this type of theatre is named Shabih Mozhek. Mostly, its basic content was scoffing the religion’s enemies. Since the Qajar rulers wre so prejudiced, they promoted the scoffing of the religion’s enemies as a discourse of power. Naturally, the characteristics mentioned about Nesereddin Shah, especially his interest in recreation, shows that in his period clowns (‘Dalghak’ in Persian) had prosperous times. These clowns were honest persons who bravely revealed, though satire and derogatory language, the government’s injustice and oppression. Standing against two strong discourses of power (the power of common-law and the power of government), these clowns took people to other aspects of life apart from formal, ordinary life: an informal life which was full of laughter and freedom far from the restrictions and prohibitions prevailing the society. Some of the elements of carnival found in the clown-play (‘Dalghak’ in Persian) include: freedom arises from participating in confrontation with the discourse of power and creating an informal attractive life which takes no head of all the current an informal attractive life which takes no heed of all the current restrictions and prohibitions. Due to his thirst for power, international trips and luxurious despotism, Nasereddin Shah understood the people’s need of recreation. Although he had no information about carnival results, as he considered recreation as a requisite of carnival, he preserved and promoted creating carnival spaces. Finding the social concepts of carnival, which is the result of creating theatre forms, shows that sociological evaluations according to social concepts and principles can advance new views in social function of art.