A vane rotary compressor has a cylinder. A main bearing and a sub bearing are coupled to the cylinder forming a compression space. The main and sub bearing each have a back pressure pocket on a surface facing the cylinder. The main bearing and the sub bearing radially support a rotation shaft. A roller coupled to the shaft is disposed within the compression space. The roller has circumferentially spaced vane slots, each vane slot extending from an open end on an outer circumferential surface of the roller to a back pressure chamber disposed within the roller at an opposite end of each vane slot. A plurality of vanes slide within the vane slots and divide the compression space into compression chambers. At least one of the back pressure chambers in the vane slots fluidly communicates with at least one of the back pressure pockets in the main and sub bearings.