Abstract: A fuel cell system includes a fuel cell, a cathode off-gas discharge channel, a gas-liquid separator, and a cover member. The gas-liquid separator includes a body, a first discharge channel including a first valve seat at an end, and a first valve device including a first valve element and a first driver. The cover member covers at least the first discharge channel and the first valve seat in the gas-liquid separator, and includes a gas channel defining portion that defines a gas channel communicating with the cathode off-gas discharge channel between the cover member and the gas-liquid separator. The gas channel is configured such that a cathode off-gas flowing into the cover member comes into contact with the first discharge channel and the first valve seat and does not come into contact with the first driver.