PROBLEM TO BE SOLVED: To provide a composition containing a monosaccharide with an elevated content and/or purity of the monosaccharide and to provide the composition containing the monosaccharide easily and at a low cost by a full hydrolysis treatment of a hemicellulose residue obtained by a prehydrolysis treatment of the hemicellulose under a specific condition.SOLUTION: The method for producing a composition containing a monosaccharide includes a prehydrolysis treatment of a hemicellulose at a pH of 0.5-2.5 and 60-120°C reaction temperature with 0.1-18 h reaction time, followed by a full hydrolysis treatment of the residue obtained in the prehydrolysis.
