Provided is a method for efficiently producing sugar and simultaneously efficiently producing ethanol. A method for producing sugar characterized by comprising a pretreatment step in which a plant-origin sugar solution is fermented by a microorganism having no sucrose-degrading enzyme and a step for producing sugar from the fermented sugar solution. A method for producing sugar characterized by comprising a pretreatment step in which a plant-origin sugar solution is fermented by a microorganism in the presence of a sucrose-degrading enzyme inhibitor and a step for producing sugar from the fermented sugar solution.