PROBLEM TO BE SOLVED: To provide a novel oligosaccharide containing mannose and fructose as constituent sugar, a method for producing the oligosaccharide, and a culture medium for microorganism culture containing the oligosaccharide.SOLUTION: The present invention provides a method for producing mannopolyocyl fructose in which: coffee beans and/or lees of coffee beans are heated at 180-250°C to obtain an oligosaccharide composition, and from the obtained oligosaccharide composition, mannopolyocyl fructose represented by the formula (1) (where n is an integer of 0-8) is separated and purified.SELECTED DRAWING: None