NOVELTY - The hydrogen generation apparatus has raw material supply unit (A), water supply unit (B), oxidation gas supply unit (C), modification unit (D), denaturation unit (E), carbon monoxide oxidation unit (F), driving time measuring unit (G) and control unit (H). Units (E,F) reduce carbon monoxide contained in produced hydrogen gas. Unit (G) measures accumulated total operation time of unit (D), and unit (H) controls the apparatus.    USE - Producing hydrogen for fuel cell system (claimed).    ADVANTAGE - The hydrogen generation apparatus prevents poisoning of platinum group catalyst of carbon monoxide oxidation portion, and has high durability.    DETAILED DESCRIPTION - The hydrogen generation apparatus has raw material supply unit, water supply unit, oxidation gas supply unit, modification unit, denaturation unit, carbon monoxide oxidation unit, driving time measuring unit and control unit. Raw material and water supplied by respective supply units are reacted. Carbon monoxide contained in hydrogen gas produced by modification unit, is reduced by the denaturation unit. Carbon monoxide contained in addition in the carbon monoxide-reduced hydrogen gas, and the oxidation gas supplied by the oxidation gas supply units, are oxidized. The carbon monoxide unit further reduces carbon monoxide. The driving time measuring unit measures the accumulated total operation time of the modification unit. The control unit controls the hydrogen generation apparatus based on the accumulated total operation time utilizing the driving measurement result.    INDEPENDENT CLAIMS are included for the following:    (1) operating method of hydrogen gas generation apparatus;    (2) fuel cell system;    (3) program for carrying out and functioning a computer; and    (4) recording medium.    DESCRIPTION OF DRAWING(S) - The figure shows an outline block diagram of hydrogen generation apparatus. (Drawing includes non-English language text).    Raw material supply (1)    Water supply (2)    Modification (3)    Denaturation (4)    CO oxidation (5)    Oxidation gas supply (6)    Denaturation temperature control (7)    Denaturation temperature detection (8)    CO oxidation temperature control (9)    CO oxidation temperature detection (10)    Fuel cell (11)    Driving time measurement (12)