NOVELTY - The system (10A) has a gas-purification apparatus (14), where dust in gas generated by a biomass gasifier (12) is removed from the apparatus. A booster (15) pressure-rises the generated gas (13A) after dust removal. A modifier (17) reforms the pressure-risen generated gas. A gas component detector (19) detects a gas component of reformed gas (18). A bypass line (21) is provided with a controlling valve (20) that bypasses the modifier and flows the generated gas to a downstream side of the modifier. A control apparatus (22) adjusts opening degree of valve according to detected gas composition.    USE - Biomass fuel gasification system for use in a chemical product synthetic system (claimed).    ADVANTAGE - The gas component detector detects the gas component of the reformed gas to detect a composition of merging gas of the reformed gas and the generated gas from which sulfur content is removed such that information of the gas composition detected with the gas component detector is sent to the control apparatus to adjust the opening degree of the controlling valve according to the composition of predetermined hydrogen concentration required with the chemical product synthesizing apparatus, thus adjusting the flow volume of the generated gas.    DETAILED DESCRIPTION - The system has a biomass selected from a group consisting of farm product, by-product, timber, plant, sweet sorghum, Pennisetum purpureum, Spirulina, and agriculture-and-forestry type waste material such as rice bran, wood chip, and coppiced timber. An INDEPENDENT CLAIM is also included for a chemical product synthetic system.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a biomass fuel gasification system.'(Drawing includes non-English language text)'    Biomass fuel gasification system (10A)    Biomass gasifier (12)    Generated gas (13A)    Gas-purification apparatus (14)    Booster (15)    Modifier (17)    Reformed gas (18)    Gas component detector (19)    Controlling valve (20)    Bypass line (21)    Control apparatus (22)