Provided are non-exposure supplied fuel quantity testing device and method of a vehicle-mounted type, and more particularly, a device formed in a trunk of a vehicle without being exposed to test whether or not the ordered fuel quantity is supplied at the time of supplying fuel. Since the device is formed so as not to be exposed, it is disable to perform an artificial tampering of a lubricator, and since the device is mounted in the trunk, it is enable to measure whether or not the ordered fuel is supplied accurately at the same time as supplying fuel. The present invention relates to a testing method using the testing device.