The present invention relates to a radio frequency identification (RFID) tag antenna and an RFID tag, in which a connection part where a radiator dipole and a T-junction are connected has a branch structure, so that an electric current can be induced in the T-junction and the radiator dipole by the branch structure, and the amount of the electric current induced in the radiator dipole can be adjusted to thereby control impedance of the RFID tag antenna in detail. The RFID tag antenna includes: a substrate; a radiator dipole symmetrically printed on the substrate in a form of meanders; and a T-junction formed between the symmetrical radiator dipoles, formed integrally with each end part of the symmetrical radiator dipoles and performing impedance matching between the radiator dipole and an RFID tag chip, wherein a connection part where the symmetrical radiator dipole and the T-junction are connected has a branch structure.