PURPOSE: To nearly completely prevent the liquid in a tank from moving during transportation for improving the driving stability by a method wherein a honeycomb structure made of plastic is installed in the tank, and the opening of the honeycomb structure is arranged in the vertical direction of a tank rulley.

CONSTITUTION: A plastic honeycomb structure 4 is arranged in a tank 2 of a tank rulley 1 and is of a honeycomb structure made of such thermoplastic resin as polyvinyl chloride resin, polyethylene, polypropylene or others. The opening direction of cells 5 (hollow parts) of the honeycomb structure 4 is arranged in the vertical direction of the tank rulley 1. Thereby, the liquid in the tank 2 is nearly completely prevented from moving during transportation without any affection on filling and discharging of the liquid to and from the tank 2, so that the driving stability can be improved.