It is represented the universal model of explanation of the ethnic cleansing in connection with the democratization process. Precondition of the emergence of the ethnic cleansing is the conflict between «Demos» and «Ethnos» where the last gains a victory. «Ethnos» is a social construct but not the ethnic difference. The organic democracies is built on the basis of «Ethnos» which forms nation state under the slogan: «we, the people», i.e. «we, the nation». There are several necessary precondition for the development of the ethnic cleansing: the political power relations, the accent on the ethnic difference, the hope of the assistance from somebody, the split of the State. The ethnic cleansing never been planned but emerges on the conflict escalation stage as the result of the radicalization of the political decision-making. The bloody ethnic cleansings are the state suppression of the specified ethnic group, ethnocide, politicide, classicidе (the voluntary mass manslaughter the whole social classes), genocide. «The dark side» of democracy is represented as its integral part from the beginning of the Modern period. In the 20th century the mechanism of the ethnic cleansing peaked in the situation of the ethnic conflicts. The phenomenon of the politicization of nationalism is the key to the ethnic cleansing which represent in the perversion of the Modernity to build the democracy in the frame of the nation state. The ethnical unity has started to assume increasing importance, as the result of the domination of «Demos» in the frame of the nation state, then the civil diversity which is the most important moment in the establishment of the democracy.