A vane rotary compressor, comprising: a casing; a cylinder provided in an inner space of the casing; a main bearing and a sub bearing forming a compression space together with the cylinder, and provided with a plurality of back pressure pockets (1313, 1323) each having a different pressure formed on a surface facing the cylinder; a rotation shaft radially supported by the main bearing and the sub bearing; a roller provided with a plurality of vane slots (1341a, 1341b, 1341c) formed along a circumferential direction and each having one end opened toward an outer circumferential surface; and a plurality of vanes (1351, 1352, 1353) slidably inserted into the vane slots (1341a, 1341b, 1341c) of the roller, and configured to divide the compression space into a plurality of compression chambers (V1, V2, V3), wherein at least one of the main bearing and the sub bearing is provided with an oil supply passage for communicating a space between an outer circumferential surface of the rotation shaft and an inner circumferential surface of the main bearing facing the outer circumferential surface of the rotation shaft with the back pressure pocket (1313, 1323) of the main bearing or a space between the outer circumferential surface of the rotation shaft and an inner circumferential surface of the sub bearing facing the outer circumferential surface of the rotation shaft with the back pressure pocket (1313, 1323) of the sub bearing, and wherein the oil supply passage communicates with a back pressure pocket (1313, 1323) having relatively low pressure among the plurality of back pressure pockets (1313, 1323), wherein the main bearing and/or the sub bearing are provided with a boss portion (1311, 1321) extending from a flange portion (1312, 1322) defining the compression space by a predetermined height, respectively, so as to radially support the rotation shaft, wherein the oil supply passage is formed through the boss portion (1311, 1321) of at least one of the main bearing and the sub bearing, characterized in that the oil supply passage is configured as a first oil supply passage (1311d1) communicating with an end surface of the boss portion (1311, 1321), and a second oil supply passage (1311d2) extending from the first oil supply passage (1311d1) so as to communicate with the back pressure pocket (1313, 1323), wherein an axial center of the first oil supply passage (1311d1) and an axial center of the second oil supply passage (1311d2) are eccentrically formed with respect to each other, wherein the first oil supply passage (1311d1) is formed such that a portion of an end surface thereof overlaps an inside of the second oil supply passage (1311d2), and wherein the oil supply passage is provided therein with a pressure reducing member axially supported on an end surface of the second oil supply passage (1311d2). a casing; a cylinder provided in an inner space of the casing; a main bearing and a sub bearing forming a compression space together with the cylinder, and provided with a plurality of back pressure pockets (1313, 1323) each having a different pressure formed on a surface facing the cylinder; a rotation shaft radially supported by the main bearing and the sub bearing; a roller provided with a plurality of vane slots (1341a, 1341b, 1341c) formed along a circumferential direction and each having one end opened toward an outer circumferential surface; and a plurality of vanes (1351, 1352, 1353) slidably inserted into the vane slots (1341a, 1341b, 1341c) of the roller, and configured to divide the compression space into a plurality of compression chambers (V1, V2, V3), wherein at least one of the main bearing and the sub bearing is provided with an oil supply passage for communicating a space between an outer circumferential surface of the rotation shaft and an inner circumferential surface of the main bearing facing the outer circumferential surface of the rotation shaft with the back pressure pocket (1313, 1323) of the main bearing or a space between the outer circumferential surface of the rotation shaft and an inner circumferential surface of the sub bearing facing the outer circumferential surface of the rotation shaft with the back pressure pocket (1313, 1323) of the sub bearing, and wherein the oil supply passage communicates with a back pressure pocket (1313, 1323) having relatively low pressure among the plurality of back pressure pockets (1313, 1323), wherein the main bearing and/or the sub bearing are provided with a boss portion (1311, 1321) extending from a flange portion (1312, 1322) defining the compression space by a predetermined height, respectively, so as to radially support the rotation shaft, wherein the oil supply passage is formed through the boss portion (1311, 1321) of at least one of the main bearing and the sub bearing, characterized in that the oil supply passage is configured as a first oil supply passage (1311d1) communicating with an end surface of the boss portion (1311, 1321), and a second oil supply passage (1311d2) extending from the first oil supply passage (1311d1) so as to communicate with the back pressure pocket (1313, 1323), wherein an axial center of the first oil supply passage (1311d1) and an axial center of the second oil supply passage (1311d2) are eccentrically formed with respect to each other, wherein the first oil supply passage (1311d1) is formed such that a portion of an end surface thereof overlaps an inside of the second oil supply passage (1311d2), and wherein the oil supply passage is provided therein with a pressure reducing member axially supported on an end surface of the second oil supply passage (1311d2).