To provide a collection method of a carbon dioxide of a vehicle mounted with a CO2 collection device which can avoid or suppress a trouble of increasing a vacant capacity which can store the carbon dioxide by the CO2 collection device and stopping at a collector to collect or discharge the carbon dioxide, without the necessity for collecting the carbon dioxide by the collector.SOLUTION: A collection method of a carbon dioxide of a vehicle mounted with a CO2 collection device, determines whether or not another vehicle having another CO2 collection device having a vacant capacity capable of storing the carbon dioxide exists around the vehicle (Steps S3, S30), and, when the other vehicle having the other CO2 collection device having the vacant capacity exists around the vehicle, communicates the CO2 collection device with the other CO2 collection device and transfers the carbon dioxide stored in the CO2 collection device to the other CO 2 collection device (Steps S5, S6, S500 and S600).SELECTED DRAWING: Figure 4