In the article it was described that in the conditions of formation market relations the informal sector has become an independent segment of the labor market, the influence of socio-demographic factors on it, as well as the functioning mechanism for market of the provision of temporary one-time work in the informal labor market and forms and types of it. When describing the functioning mechanism of the market of the provision of temporary one-time work, it was used the method of sociological research, which was conducted by the author, and from the point of view of economy theory, it was clarified that the new legality of that market.