The invention provides a direct methanol fuel cell system comprising a fuel cell main body comprising an anode, a cathode, an electrolyte membrane provided between the anode and the cathode, and a feed tank containing a methanol-containing liquid fuel to be fed to the anode, a first liquid fuel storage tank which contains a methanol-containing liquid fuel to be supplied into the feed tank, a second liquid fuel storage tank which contains a methanol-containing liquid fuel to be supplied into the first liquid fuel storage tank, and a liquid level change detecting mechanism which detects changes in the level of the liquid fuel stored in the first liquid fuel storage tank.