NOVELTY - A hydrogen-producing apparatus (10) comprises solution container (14), reaction container (12), liquid feeding path, detection unit, measurement unit (18) and residual amount calculation unit (19). The detection init detects feeding point and end point of reaction solution. The measurement unit measures length of liquid feeding time of reaction solution. The residual amount calculation unit calculates residual mount of hydrogen by reaction with reaction material solid and generated reaction solution based on measured value of measurement unit.    USE - Hydrogen-producing apparatus is used for fuel cell system (claimed).    ADVANTAGE - The apparatus has reduced power consumption and easily obtains hydrogen residual amount. The fuel cell comprising hydrogen-producing apparatus has high electric power generation and economical efficiency.    DETAILED DESCRIPTION - A hydrogen-producing apparatus comprises solution container, reaction container, liquid feeding path, detection unit, measurement unit and residual amount calculation unit. The solution container accommodates reaction solution (13). The reaction container contains reaction material which generates hydrogen by reacting with reaction solution. The liquid feeding path connects solution container and reaction container. The internal pressure of reaction container is lower than a specified pressure, the liquid in solution container is fed to reaction container. The detection init detects liquid feeding point and end point of reaction solution from solution container. The measurement unit measures the length of liquid feeding time of reaction solution, by setting detection means as trigger. The residual amount calculation unit calculates the residual mount of hydrogen by reaction with solid reaction material (11) and generated reaction solution based on measured value of measurement unit.    DESCRIPTION OF DRAWING(S) - The drawing shows sectional view of hydrogen-producing apparatus. (Drawing includes non-English language text).    Hydrogen-producing apparatus (10)    Solid reaction material (11)    Reaction container (12)    Reaction solution (13)    Solution container (14)    Measurement unit (18)    Residual amount calculation unit (19)