A double check valve is provided to realize complete checking for preventing reverse flow of fluid through vertical motion by tare instead of plate rotation. A valve body is mounted between a rear end of a water-meter and a water supply pipe for introducing water from the rear end of the water-meter. A first moving part is mounted in the valve body and lowers by the tare when the water is not in use for preventing water from flowing reversely from the water supply pipe to the water-meter primarily. A second moving part(30) is coupled in the first moving part and lowers by the tare when the water is not in use for preventing water from flowing reversely from the water supply pipe to the water-meter secondarily.
