Fuel cell system

A fuel cell system (101) includes a fuel tank (11) configured to store a fuel at a pressure higher than atmospheric pressure; a vaporizer (12) configured to vaporize a fuel; a reformer (13) configured to reform the vaporized fuel into a hydrogen rich gas; a CO gas removal apparatus (14) configured to remove CO gas in the hydrogen rich gas; and a cell unit (15) configured to generate electricity by allowing the hydrogen rich gas to react with oxygen.