The principles and methodology of mapping the population density of a sparsely populated area has been developed using the example of the Irkutsk region. For the most part of the Irkutsk region is not characterized by a continuous area settlement, but linear and focal with an extremely rare network of permanent settlements, except for its southern part along the Trans-Siberian railway. Of the three possible types of population density maps there are contours, choropleths and quantitative areas for a rarely inhabited and little populated region, and only the latter type is suitable. The borders of the inhabited territory are carried out in a formal way. To draw the boundaries of the area populated area by the method of spots we need the radius of the buffer 3 km. Inhabited zones, formed by chains of settlements along the transport routs, adjoin the entirely populated territory. A quantitative map of the density by areas of the rural and urban population was constructed. The map helps you visualize the quantitative differentiation of the populated areas seeing population density and distinguish the unsettled territories. A map of inhabited areas can be the basis for mapping demographic, ethnographic, ecological and socio-economic characteristics of the population.