An RFID reader, RFID tag, and method thereof for performing a write check of tag data. According to an exemplary embodiment, the RFID reader may include: a transmitter to transmit a write check command to an RFID tag; a receiver to receive a response including a check value of data, which needs a write check, from an RFID tag that has received the write check command; and a controller to perform information transmission and reception processes, and check data written on the RFID tag by using the received response.