An RFID tag attached to an object and transmitting a signal that corresponds to identification information includes an RFID tag chip that modulates the signal according to the identification information and an RFID tag antenna that transmits the modulated signal. The RFID tag antenna includes a dielectric material, a radiating patch, and a slit. The dielectric material has a polyhedral shape and includes a first surface that contacts the object and a second surface that is parallel with the first surface, the radiating patch is formed on at least a part of the second surface and radiates electromagnetic to waves, and the slit is formed on at least a part of the radiating patch to expose the dielectric material.