An RFID tag comprising: an antenna configured to perform transmission/reception of signals with a reader/writer; and an IC chip to which the antenna is connected, characterized in that the RFID tag comprises: an insulating layer on which the antenna is formed; a plurality of connection terminals (5A, 5B, 5C, 5D) inside outer peripheral edges of the insulating layer; and an annular antenna-forming area formed on the entire periphery of the insulating layer, wherein the antenna is formed into a loop, with one of the plurality of connection terminals (5A, 5B, 5C, 5D) serving as a starting point and any one of the remaining connection terminals (5A, 5C, 5D) serving as an endpoint, so that a conductor line is turned within the antenna-forming area, wherein the conductor line has a cross-sectional shape in a longitudinal direction being larger than a cross-sectional shape in a lateral direction, wherein turns of the conductor line that are adjacent to each other in a radial direction orthogonal to a turned direction of the antenna have the same line width, wherein the line width is set within a range of 2 μm to 7 μm, wherein a spacing between the turns of the conductor line that are adjacent to each other in the radial direction is set within a range of 2 μm to 7 μm, wherein the insulating layer is a package of the IC chip, wherein the antenna is provided on the package of the IC chip, wherein the IC chip is formed to have a rectangular shape, and wherein the plurality of connection terminals (5A, 5B, 5C, 5D) are provided at corners of the insulating layer and inside outer peripheral edges of the insulating layer. an antenna configured to perform transmission/reception of signals with a reader/writer; and an IC chip to which the antenna is connected, characterized in that the RFID tag comprises: an insulating layer on which the antenna is formed; a plurality of connection terminals (5A, 5B, 5C, 5D) inside outer peripheral edges of the insulating layer; and an annular antenna-forming area formed on the entire periphery of the insulating layer, an insulating layer on which the antenna is formed; a plurality of connection terminals (5A, 5B, 5C, 5D) inside outer peripheral edges of the insulating layer; and an annular antenna-forming area formed on the entire periphery of the insulating layer, wherein the antenna is formed into a loop, with one of the plurality of connection terminals (5A, 5B, 5C, 5D) serving as a starting point and any one of the remaining connection terminals (5A, 5C, 5D) serving as an endpoint, so that a conductor line is turned within the antenna-forming area, wherein the conductor line has a cross-sectional shape in a longitudinal direction being larger than a cross-sectional shape in a lateral direction, wherein turns of the conductor line that are adjacent to each other in a radial direction orthogonal to a turned direction of the antenna have the same line width, wherein the line width is set within a range of 2 μm to 7 μm, wherein a spacing between the turns of the conductor line that are adjacent to each other in the radial direction is set within a range of 2 μm to 7 μm, wherein the insulating layer is a package of the IC chip, wherein the antenna is provided on the package of the IC chip, wherein the IC chip is formed to have a rectangular shape, and wherein the plurality of connection terminals (5A, 5B, 5C, 5D) are provided at corners of the insulating layer and inside outer peripheral edges of the insulating layer.