A method of producing a sugar liquid from biomass includes decomposing a fermentation inhibitor contained in a sugar aqueous solution obtained from biomass with a microorganism incapable of utilizing glucose and/or xylose or a crude enzyme derived from the microorganism, wherein the fermentation inhibitor includes one or more compounds selected from the group consisting of courmaric acid, coumaramide, ferulic acid, ferulamide, vanillin, vanillic acid, acetovanillone, furfural, and 3-hydroxymethylfurfural.