To provide a fuel shutoff valve 10 regulating tank internal pressure to prescribed pressure or below, even if the tank internal pressure is raised due to generation of excessive fuel vapor, in a fuel liquid level closing a communication hole 35c when fuel is full.

This fuel shutoff valve 10 includes a casing 20 having a valve chamber 30S and a float mechanism 50 stored in the valve chamber 30S to be elevated and lowered according to the fuel liquid level in the fuel tank FT. In a side wall part 32 of the casing 20, an orifice hole 32a for connecting the fuel tank FT and the valve chamber 30S is formed. In a bottom plate 35, the communication hole 35c is formed. When the communication hole 35c is closed by fuel, fuel is introduced to the valve chamber 30S by a difference between the valve chamber 30S and tank internal pressure, and the float mechanism 50 performs a closing operation. A pressure-regulating valve 70 to be a one-way valve is opened when the tank internal pressure exceeds valve opening pressure P1 set to be higher value than the tank internal pressure when feeding fuel and maintains the tank internal pressure to the prescribed pressure or below.