NOVELTY - The method for supplying hydrogen-rich fuel to a fuel cell, comprises feeding (201) a specific amount of the fuel into the fuel cell, determining (202) a specific monitoring period according to a characteristic value measured from the fuel cell when subjected to a load, detecting if the load is varying during the specific monitoring period, determining whether the specific amount of fuel is enough if the load is not changed, and obtaining a first and a second characteristic value of the fuel cell before the end of the specific monitoring period.    USE - The method is useful for supplying hydrogen-rich fuel to a fuel cell, which is useful for all industrial requirements such as automobile industry and Computer, Communication and Consumer Electronic industry (3C industry).    ADVANTAGE - The method is capable of measuring the characteristic value of the fuel cell when the fuel cell is subjected to a load while basing on the measurement to determine whether the load is varying thus effectively controlling the timing for supplying fuel to the fuel cell and capable of regulating fuel concentration and changing fuel supply of the fuel cell according to a loading current measured from the fuel cell thus enabling the fuel cell to generate power in respond to the variation of the load and optimizing the performance of the fuel cell.    DETAILED DESCRIPTION - The method for supplying hydrogen-rich fuel to a fuel cell, comprises feeding (201) a specific amount of the fuel into the fuel cell, determining (202) a specific monitoring period according to a characteristic value measured from the fuel cell when subjected to a load, detecting if the load is varying during the specific monitoring period, determining whether the specific amount of fuel is enough if the load is not changed, obtaining a first and a second characteristic value of the fuel cell before the end of the specific monitoring period, making an evaluation to determine whether the second characteristic value is smaller than the first characteristic value, obtaining (208) a third characteristic value of the fuel cell before a specific point of time after the end of the specific monitoring period when the second characteristic value is larger than the first characteristic value, obtaining (209) a fourth characteristic value of the fuel cell at the specific point of time, making (203) an evaluation to determine whether the variation of the characteristic value exceeds a threshold value, making an evaluation to determine whether the fourth characteristic value is smaller than the third characteristic value when the variation of the characteristic value not exceeds the threshold value, obtaining a first slope from a curve profiling characteristic value of the fuel cell at the end of the specific monitoring period, injecting the specific amount of fuel into the fuel cell when the first slope is a negative value, obtaining a second slope from the characteristic curve of the fuel cell before a specific point time after the end of the monitoring period when the first slope is a positive value, making an evaluation to determine whether the variation of the characteristic value exceeds a threshold value, determining whether the second slope is a negative value when the characteristic value not exceeds the threshold value and if so the flow proceeds back to the feeding step for injecting the specific amount of fuel into the fuel cell, and proceeding the second slope obtaining step when the second slope is a positive value. If the second characteristic value is smaller and if the fourth characteristic value is smaller than the third characteristic value, the flow proceeds back to the feeding step for injecting the specific amount of the fuel into the mixing tank of the fuel cell system. The third characteristic value obtaining step is preceded again when the fourth characteristic value is larger than the third characteristic value. The characteristic value consists of current, voltage and/or power measured from the fuel cell. The load is considered to be varying when the variation of a characteristic value exceeds a predetermined threshold value at any time during the specific monitoring period. The feeding step is preceded again when the load is increased and the determination step is preceded again when the load is decreased. The increased load is determined when the characteristic value changes from low to high, and the decreased load is determined when the characteristic value changes from high to low. The changing of the characteristic value is determined by changing the characteristic value from low to high when a slope obtained from a curve profiling the variation of the characteristic value is a positive value and changing the characteristic value from high to low when the slope obtained from the curve profiling the variation of the characteristic value is a negative value. The step of changing the characteristic value from high to low is determined by evaluating whether the difference of characteristic values measured before a specific point of time and at the specific point of time is positive, and the step of changing the characteristic value from low to high is determined by evaluating whether the difference of characteristic values measured before a specific point of time and at the specific point of time is negative. The load is considered to be varying when the variation of the characteristic value exceeds a predetermined threshold value at any time during the specific monitoring period. The first characteristic value is a value consisting of the minimum voltage, voltage and/or power measured during the specific monitoring period, and is a value consisting of an average and a root mean square (RMS) of characteristic values associated with a time zone in the specific monitoring period. The third characteristic value is a value consisting of an average and a root mean square of characteristic values associated with a time zone before the specific point of time, and minimum characteristic value measured from the fuel cell associated with a time zone before the specific point of time.    DESCRIPTION OF DRAWING(S) - The diagram shows a flow chart of a method for supplying fuel to a fuel cell.    Feeding a specific amount of the fuel into the fuel cell (201)    Determining a specific monitoring time period (202)    Making an evaluation to determine whether the variation of the characteristic value exceeds a threshold value (203)    Obtaining a third characteristic value of the fuel cell (208)    Obtaining a fourth characteristic value of the fuel cell. (209)