A fuel cell module comprises: at least one cell stack including a plurality of single fuel cells supplied with a fuel gas and an oxidizing gas to generate power; a sealable housing accommodating the at least one cell stack and forming a power generation chamber inside the housing; a pressure vessel accommodating the housing; and an oxidizing gas supply pipe for supplying the oxidizing gas to the cell stack. At least one pressure equalizing opening is formed in the housing to allow communication between inside and outside of the housing. The at least one pressure equalizing opening includes only one pressure equalizing opening, or a plurality of pressure equalizing openings in which a distance between a pressure equalizing opening in the highest position and a pressure equalizing opening in the lowest position is within 0.1H, where H is a height of the housing.