Time authentication device, time authentication method, computer program, recording medium, integrated circuit, and time authentication system

A time authentication device capable of selecting only a correct timepiece whose way of time advancement measured by a timepiece of another device is within an allowable range determined with a timepiece of the time authentication device as the standard. In a distribution device (11) as a time authentication device, a section (104) for storing information corresponding to time stores both reproduction device time measured by a timepiece section (203) of a reproduction device (12) and distribution device time measured by a timepiece section (103) when the reproduction device time is received. A time authentication section (107) obtains object time, measured by the timepiece section (203), from the reproduction device (12), obtains authentication time, which is the time at which the object time is obtained from timepiece means, and sequentially calculates a first difference (authentication time - distribution device time), a second difference (= object time - reproduction device time), and an authentication difference (= first difference - second difference). When the authentication difference is equal to or less than a predetermined threshold value, the time authentication section (107) determines that the timepiece section (203) of the reproduction device (12) is correct.