To provide novel xylanase.SOLUTION: Polypeptide has an amino acid sequence of the following (A) or (B), and has endo-type xylanase activity: (A) an amino acid sequence having identity of 80% or more with a specific amino acid sequence, (B) an amino acid sequence having amino acid sequence in which one or several pieces of amino acid residue is substituted, deleted, inserted and/or added in the specific amino acid sequence. A method for producing xylooligosaccharide in which the polypeptide is allowed to work on xylan.SELECTED DRAWING: None【課題】新たなキシラナーゼの提供。【解決手段】下記(A)または(B)のアミノ酸配列を有し、エンド型キシラナーゼ活性を有するポリペプチド:(A)ある特定のアミノ酸配列と80%以上の同一性を有するアミノ酸配列、(B)前記ある特定のアミノ酸配列において1又は数個のアミノ酸残基が置換、欠失、挿入及び/又は付加されたアミノ酸配列を有するアミノ酸配列。該ポリペプチドをキシランに作用させる、キシロオリゴ糖の製造方法。【選択図】なし