The article is devoted to the problem of understanding of the moral character of the member of a revolutionary party by ideologists of populists late in the 19th century. It analyses the ideas of S.G. Nechaev and P.N. Tkachev. They considered that morality, the revolutionary's personal life and revolution were not combined. On the contrary P.L. Lavrov and M.A. Bakunin spoke about morality and knowledge as the main qualities of a revolutionary. They define the affirmation of socialism after revolution.