NOVELTY - A direct methanol fuel cell system comprises: (i) a power generating unit; (ii) a characteristic-measuring mechanism that measures a current-voltage characteristic of the power generating unit; (iii) an external load supply mechanism that supplies an electric power of the power generating unit to an external load; (iv) a methanol aqueous solution container; and (v) a fuel cartridge that stores methanol aqueous solution to be replenished in the container.    USE - For generating power, or for use in portable electronic appliances.    ADVANTAGE - The system has a less load on environments. It is capable of stably supplying electric power to a load over a long period. It is capable of driving electronic appliances using a battery as driving power source, e.g. small portable appliances.    DETAILED DESCRIPTION - A direct methanol fuel cell system comprises:    (a) a power generating unit (100) including an anode electrode, a cathode electrode, an electrolyte layer (105) provided between the anode and cathode electrodes, an anode fluid channel (109) that supplies methanol aqueous solution to the anode electrode, and a cathode fluid channel (115) that supplies air to the cathode electrode;    (b) a characteristic-measuring mechanism that measures a current-voltage characteristic of the power generating unit;    (c) an external load supply mechanism that supplies an electric power of the power generating unit to an external load on the basis of the current voltage characteristic;    (d) a methanol aqueous solution container that stores methanol aqueous solution to be supplied to the anode fluid channel; and    (e) a fuel cartridge that stores methanol aqueous solution to be replenished in the methanol aqueous solution container.    DESCRIPTION OF DRAWING(S) - The figure is a diagram showing a structure of a direct methanol fuel cell power generating device.    Power generating unit (100)    Electrolyte layer (105)    Anode fluid channel (109)    Cathode fluid channel (115)    Pressure regulating valve (130)