A terminal device that executes an authentication sequence through wireless communication with an external device includes a communication unit configured to transmit or receive a radio signal to be used for the authentication sequence, a first measurement unit configured to measure a change in a radio wave intensity for at least a part of the radio signal received by the communication unit; a second measurement unit configured to measure a change in a posture or a position of the terminal device, and a controller configured to determine whether there is a correlation between a measurement result of the first measurement unit and a measurement result of the second measurement unit, i) continue the authentication sequence when the controller determines that there is the correlation, and ii) interrupt the authentication sequence when the controller determines that there is no correlation.