NOVELTY - The fuel supply system has electric generating unit (20), fuel storage unit (10) to store supply fuel to unit (10), recycling unit (11) to store unreacted fuel and water emitted from unit (10), fuel transferring unit (30) to transfer fuel stored in fuel storage unit to recycling unit, fuel transferring unit (31) to transfer fuel within recycling unit to unit (10), and control unit (50) to calculate consumption speed of fuel in unit (10) based on current generated by unit (10), and control volume flow rate of fuel transferred from fuel storage unit to recycling unit.    USE - Fuel supply system is used for supplying fuel to fuel cell system (claimed) such as direct methanol fuel cell system.    ADVANTAGE - The fuel supply system accurately controls concentration of fuel based on intensity of current measured by fuel cell system, without using concentration sensor, and provides fuel cell system having high stability and efficiency.    DETAILED DESCRIPTION - The fuel supply system has an electric generating unit (20) to generate electric energy by electrochemical reaction between fuel and an oxidant, a fuel storage unit (10) to store an supply fuel to electric generating unit, a recycling unit (11) to store unreacted fuel and water emitted from electric generating unit, a fuel transferring unit (30) to transfer fuel stored in fuel storage unit to recycling unit, a fuel transferring unit (31) to transfer fuel within recycling unit to electric generating unit, and a control unit (50) to calculate consumption speed of fuel consumed in electric generating unit based on current generated by electric generating unit, and control the volume flow rate of fuel transferred from fuel storage unit to recycling unit based on calculated consumption speed.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram of the direct methanol fuel cell system using fuel supply system.    Fuel storage unit (10)    Recycling unit (11)    Electric generating unit (20)    Fuel transferring units (30,31)    Control unit (50)