Patent ID: 8347197

Claim:
A terminal device comprising: a time measuring unit which is configured to measure time; an estimated error memory unit which is configured to store an estimated error between a measured time measured by the time measuring unit and current time; a time information requesting unit which is configured to request another terminal device to transmit a measured time and an estimated error of the other terminal device; a time information transmitting unit which is configured to transmit the measured time measured by the time measuring unit and the estimated error stored in the estimated error memory unit to a requesting terminal device in response to a request from the requesting terminal device; a time information receiving unit which is configured to receive the measured time and the estimated error of the other terminal device requested by the time information requesting unit; an estimated error calculating unit which is configured to calculate an error containing the estimated error of the other terminal device received by the time information receiving unit as an updating-use estimated error; and a time updating unit which is configured, when the updating-use estimated error calculated by the estimated error calculating unit is smaller than the estimated error stored in the estimated error memory unit, to store the updating-use estimated error in the estimated error memory unit as an updated estimated error thus updating the estimated error, and to adjust the measured time measured by the time measuring unit based on the measured time of the other terminal device received by the time information receiving unit.