A direct methanol type fuel cell system provided with a tank for storing an antifreeze that is injected into at least said unit cell or a cell stack and held in place at the time of stand-by operation of the direct methanol type fuel cell system. At the time of starting operation an oxidant gas is supplied to the cathode side and the antifreeze is removed from the unit cell or the cell stack. After starting operation, the passage between the antifreeze tank and the unit cell or the cell stack is closed and an aqueous solution of methanol is supplied as liquid fuel from a fuel tank to the anode side.