A solid-oxide fuel cell system includes: a fuel cell unit including a solid-oxide fuel cell including an anode gas channel and a cathode gas channel and a mixer; an electric power generation raw material supplier; a combustible gas channel extending from the electric power generation raw material supplier to a downstream end of the anode gas channel; an oxidizing gas supplier; and a controller operative to, after electric power generation of the fuel cell unit is stopped, control the electric power generation raw material supplier to supply to the combustible gas channel the electric power generation raw material, the amount of which compensates for contraction of gas in the combustible gas channel due to temperature decrease of the fuel cell unit and also control the oxidizing gas supplier to supply the oxidizing gas to the cathode gas channel in accordance with the supply of the electric power generation raw material.