A low-loss and flexible transmission line-integrated multi-port antenna for a mm Wave band, comprising: a plurality of antennas arranged on different substrate layers to form a multi port; and a plurality of transmission lines corresponding to the plurality of antennas, respectively, in which central conductors used as signal lines of the transmission lines are integrated with corresponding electricity feeding portions of the antennas and arranged on different layers, wherein the antennas each comprise: a ground plate (410, 610), a dielectric substrate (420, 520, 620) formed as a dielectric having a certain thickness on the ground plate (410, 610); a signal conversion portion (1612, 1622, 1632, 1642, 530, 630) formed on the dielectric substrate (1611, 1621, 1631, 1641, 420, 520, 620) and configured to convert an electrical signal of a mobile communication terminal into an electromagnetic wave signal and radiate the electromagnetic wave signal into the air or to receive an electromagnetic wave signal in the air into an electrical signal of a mobile communication terminal; and an electricity feeding portion (1613, 1623, 1633, 1643) formed on the dielectric substrate and connected to the signal conversion portion, wherein the transmission lines (1615, 1625, 1635, 1645) each comprise: a central conductor (1617, 1627, 1637, 710, 810) having one end integrated with the electricity feeding portion of the antenna and configured to transfer the transmitted or received electrical signal; an external conductor (720, 820) having the same axis as that of the central conductor and surrounding the central conductor in an axial direction of the central conductor so as to shield the central conductor; and a dielectric (730, 830) filling the space formed between the central conductor and the external conductor in the axial direction, and wherein the dielectric substrate (420, 520, 620) used in the antenna and the dielectric (730, 830) used in the transmission line is a low-loss nanosheet material formed as a nanosheet including a plurality of air spaces formed by electrospinning a resin at a high voltage. a plurality of antennas arranged on different substrate layers to form a multi port; and a plurality of transmission lines corresponding to the plurality of antennas, respectively, in which central conductors used as signal lines of the transmission lines are integrated with corresponding electricity feeding portions of the antennas and arranged on different layers, wherein the antennas each comprise: a ground plate (410, 610), a dielectric substrate (420, 520, 620) formed as a dielectric having a certain thickness on the ground plate (410, 610); a signal conversion portion (1612, 1622, 1632, 1642, 530, 630) formed on the dielectric substrate (1611, 1621, 1631, 1641, 420, 520, 620) and configured to convert an electrical signal of a mobile communication terminal into an electromagnetic wave signal and radiate the electromagnetic wave signal into the air or to receive an electromagnetic wave signal in the air into an electrical signal of a mobile communication terminal; and an electricity feeding portion (1613, 1623, 1633, 1643) formed on the dielectric substrate and connected to the signal conversion portion, wherein the transmission lines (1615, 1625, 1635, 1645) each comprise: a ground plate (410, 610), a dielectric substrate (420, 520, 620) formed as a dielectric having a certain thickness on the ground plate (410, 610); a signal conversion portion (1612, 1622, 1632, 1642, 530, 630) formed on the dielectric substrate (1611, 1621, 1631, 1641, 420, 520, 620) and configured to convert an electrical signal of a mobile communication terminal into an electromagnetic wave signal and radiate the electromagnetic wave signal into the air or to receive an electromagnetic wave signal in the air into an electrical signal of a mobile communication terminal; and an electricity feeding portion (1613, 1623, 1633, 1643) formed on the dielectric substrate and connected to the signal conversion portion, wherein the transmission lines (1615, 1625, 1635, 1645) each comprise: a central conductor (1617, 1627, 1637, 710, 810) having one end integrated with the electricity feeding portion of the antenna and configured to transfer the transmitted or received electrical signal; an external conductor (720, 820) having the same axis as that of the central conductor and surrounding the central conductor in an axial direction of the central conductor so as to shield the central conductor; and a dielectric (730, 830) filling the space formed between the central conductor and the external conductor in the axial direction, and wherein the dielectric substrate (420, 520, 620) used in the antenna and the dielectric (730, 830) used in the transmission line is a low-loss nanosheet material formed as a nanosheet including a plurality of air spaces formed by electrospinning a resin at a high voltage.