A user equipment (1, 101) for performing post-authentication communication with a communication equipment (2, 102) after personal authentication of the user; the user equipment (1, 101) comprising: an authentication unit for performing the personal authentication of the user; a communication unit for communicating with the communication equipment (2, 102); and a communication equipment ID storage unit for storing first communication equipment identifying information; an authentication control unit (12, 112) for receiving the first communication equipment identifying information from the communication equipment (2, 102) connected to the communication unit, storing the first communication equipment identifying information into the communication equipment ID storage, and permitting the authentication unit to execute the personal authentication of the user when receiving authentication start instructing information from the communication equipment (2, 102) connected to the communication unit, after receiving the first communication equipment identifying information, characterised in that the authentication control unit (12, 112) permits the authentication unit to execute the personal authentication of the user for a predetermined time after receiving the authentication start instructing information; and the user equipment (1, 101) comprises a post-authentication communication control unit (17, 117) for receiving second communication equipment identifying information from the communication equipment (2, 102) connected to the communication unit, performing the post-authentication communication connected to the communication unit after the authentication unit succeeds in the personal authentication of the user, and permitting post-authentication communication only when the second communication equipment identifying information matches the first communication equipment identifying information. an authentication unit for performing the personal authentication of the user; a communication unit for communicating with the communication equipment (2, 102); and a communication equipment ID storage unit for storing first communication equipment identifying information; an authentication control unit (12, 112) for receiving the first communication equipment identifying information from the communication equipment (2, 102) connected to the communication unit, storing the first communication equipment identifying information into the communication equipment ID storage, and permitting the authentication unit to execute the personal authentication of the user when receiving authentication start instructing information from the communication equipment (2, 102) connected to the communication unit, after receiving the first communication equipment identifying information, receiving the first communication equipment identifying information from the communication equipment (2, 102) connected to the communication unit, storing the first communication equipment identifying information into the communication equipment ID storage, and permitting the authentication unit to execute the personal authentication of the user when receiving authentication start instructing information from the communication equipment (2, 102) connected to the communication unit, after receiving the first communication equipment identifying information, receiving second communication equipment identifying information from the communication equipment (2, 102) connected to the communication unit, performing the post-authentication communication connected to the communication unit after the authentication unit succeeds in the personal authentication of the user, and permitting post-authentication communication only when the second communication equipment identifying information matches the first communication equipment identifying information.