PURPOSE: To provide a subtank control system which can detect the generation of an abnormal condition such as a generation of cracking and a trouble in a piping system of a valve, a pump, pipes, and the like, without delay, so as to stop the feeding of a fuel, and can prevent the generation of a fire accident comes from the fuel leakage.

CONSTITUTION: In this subtank control system, a center gauge 20 is provided in a main tank 11 as the detecting means to detect the fuel feeding condition, and an ECU 22 which decides that it is an abnormal condition when the feeding speed of the fuel detected by the center gauge 20 does not reach a specific value, makes a valve 15 in the closed condition, and stops the driving of a pump 14, is also provided.