To solve the problem that in a conventional congestion information acquisition system, a length of a congestion exceeding a section in which an observation device is set cannot be obtained.

An on-vehicle device is provided with a positional-information acquisition means used to acquire positional information; a speed detection means used to detect a speed; a congestion decision means used to decide the congestion on the basis of the speed and on the basis of a stored individual congestion decision condition; an individual-congestion-information creation means by which individual congestion information is created on the basis of the positional information and the speed when the congestion is decided by the congestion decision means; and an individual- congestion-information transmission means used to transmit the individual congestion information. A congestion-information control device is provided with an individual- congestion-information reception means used to receive a plurality of pieces of individual congestion information; and an original-congestion-information creation means used to create original congestion information on the basis of the plurality of pieces of individual congestion information. By both devices, also the congestion information on a road on which the observation device of a vehicle is not installed can be acquired.