A transportation management system for a tank container allowed to be placed on a container freight car, the tank container including a vessel capable of accommodating liquefied natural gas and a frame body which supports the vessel, the transportation management system includes a vessel management device and a transportation management device to communicate with the vessel management device. The vessel management device includes a vessel information detection unit to detect vessel information of the vessel included in the tank container, and a vessel management device-side communication unit to transmit the vessel information detected by the vessel information detection unit to the transportation management device. The transportation management device includes a transportation management device-side communication unit to receive the vessel information from the vessel management device, and an output control unit to output warning information based on the vessel information received from the vessel management device, to an output unit.