It is intended to obtain a food material which contains a mannooligosaccharide and can be used in a wide range of application by a simple method. A mannooligosaccharide-containing food composition is obtained by taking endosperms out of coconut fruits, subjecting slurry obtained by grinding the endosperms to solid-liquid separation thereby to obtain a solid, defatting the obtained solid until the oil and fat content becomes 1% by weight or less, and performing a treatment so as to hydrolyze mannan contained in the defatted solid, or in the case where the defatting treatment is not performed, allowing a mannan-degrading enzyme which does not substantially have a lipase activity to act on the solid.