A fuel cell system according to the present invention includes: a hydrogen generator (12) including a burner (4) which is detachably accommodated in the hydrogen generator (12) in a manner to allow the burner (4) to be detached from and attached to the hydrogen generator (12) through the top of the hydrogen generator (12); a stack (5) configured to generate power by causing hydrogen generated by the hydrogen generator (12) and an oxidizing gas to react with each other; and a main body package (1) which includes at least a top plate (2) and within which the hydrogen generator (12) and the stack (5) are disposed. Detachable piping (31), which is detachably configured, is provided above the hydrogen generator (12). Space that is formed above the burner (4) when the detachable piping (31) is removed from the main body package (1) has a size larger than or equal to the size of the burner.