PURPOSE: To provide a fuel cell ventilating device of such a structure as capable of keeping the differential pressure between two compartments continuously to the specified value set previsouly, as allowing a combustible gas to intrude from the combustible gas reactor accommodating compartment into the communication apparatus accommodating compartment, and thereby removing such inconvenience as touching the communication apparatus.

CONSTITUTION: Inside of an enclosure 1 is partitioned by a bulkhead 2 into a communication apparatus accommodating compartment 4 and a combustible gas reactor accommodating compartment 6. The communication apparatus accommodating compartment 4 is fitted with an air suction filter 7A and ventilation fan 8A while the combustible gas reactor accommodating compartment 6 is equipped with another air filter 7B and ventilation fan 8B. The bulkhead 2 is furnished with an opening 9 and fitted with a differential pressure adjusting damper 10 composed of a mounting frame 11, a damper plate 13 movably installed thereon 11 through a degree-of-opening adjusting stud 12, and a spring for adjusting the position of the damper plate 13.