To carry liquid such as water, etc., by using a load carrying platform of a dump car.

A cover body is provided on an upper part opening part on a load carrying platform 1 of a dump car, the cover body is opened by revolving a cover body shaft 4b by a cylinder device 8, etc., liquid such as water, etc., is injected from above and loaded, the cover body is closed and the liquid is carried. A connecting part of members to constitute the load carrying platform 1 is packing-sealed and made watertight. At the time of taking out the liquid such as water, etc., it is pumped out by a pump, etc., from above or discharged from a lower end of a rear plate 1c of a rear part by inclining the load carrying platform 1. When it is needless to carry the liquid such as water, etc., it is possible to use the dump car as an ordinary dump car.