A check valve is disposed in a hydrogen offgas circulation path which is connected to a fuel cell so as to flow the hydrogen offgas only in one direction. Inside a valve housing, a first compression chamber and a second compression chamber are provided such that a bulkhead is disposed therebetween. In the bulkhead 14, a first communication hole 18 and a second communication hole 19 are formed so as to communicate between the first compression chamber and the second compression chamber. In a first reed valve, an opening end is disposed upward and a fixed end is disposed downward. In a second reed valve, an opening end is disposed downward and a fixed end is disposed upward. By doing this, operability in the check valve after water has frozen can be improved.