Xylooligosaccharide is produced from a lignocellulose pulp by enzyme-treating a lignocellulose pulp with hemicellulase, filtering the resultant reaction mixture to separate a liquid fraction from the enzyme-treated pulp, subjecting the separated liquid fraction to a permeation treatment through a separation membrane to separate a non-permeated fraction containing xylooligosaccharide-lignin complex with an increased concentration from a permeated fraction, collecting the non-permeated fraction, and separating and recovering xylooligosaccharide from the collected non-permeated fraction.