The fuel cell state determination method determines the internal state of a fuel cell that generates electricity by receiving a supply of anode gas and cathode gas. The fuel cell state determination method comprises steps of: detecting a decrease in the reaction resistance value of a cathode pole which is caused by a hydrogen generation reaction occurring at the cathode pole due to the fuel cell entering an oxygen-deficient state; and determining the oxygen-deficient state on the basis of the detection of the decrease in the reaction resistance value.