To enable instant gas shut-off even when an earthquake occurs when gas is being used by users.

The flow velocity in a passage for supplying gas is detected by a flow velocity detecting means 14, and is converted to a flow velocity value by a flow velocity operating means 15 from signals of the flow velocity detecting means 14, and the flow rate is operated from the flow velocity by a flow rate operating means 16. On the other hand, when an earthquake is detected by a bodily sensed earthquake detecting means 9, a shut-off judging means 17 judges whether it is an earthquake or not, and further judges whether the use of gas should be stopped or not from signals of the flow rate operating means 16. If gas appliance are being used when an earthquake occurs, the shut-off judging means drives a shut-off means 4 to shut off the passage.