Provided is an invention relating to a method for measuring anti-WT1 antibodies in a sample according to which the anti-WT1 antibodies can be measured and evaluated more accurately and to use of the method. A method for measuring anti-WT1 antibodies in a sample, characterized in using: a polypeptide having antigen properties against anti-WT1 antibodies, selected from a polypeptide comprising an amino acid sequence of positions 294-449 in SEQ ID NO: 1, a partial polypeptide of said polypeptide, and a polypeptide comprising an amino acid sequence in which one or several amino acids are removed, replaced, or added with respect to the amino acid sequence constituting the above polypeptides and/or a polypeptide having antigen properties against anti-WT1 antibodies, selected from a polypeptide comprising an amino acid sequence of positions 181-324 in SEQ ID NO: 1, a partial polypeptide of said polypeptide, and a polypeptide comprising an amino acid sequence in which one or several amino acids are removed, replaced, or added with respect to the amino acid sequence constituting the above polypeptides.Cette invention concerne un procédé de mesure danticorps anti-WT1 dans un échantillon qui permet de mesurer et dévaluer plus précisément les anticorps anti-WT1 et lutilisation dudit procédé. Le procédé de mesure danticorps anti-WT1 dans un échantillon selon linvention est caractérisé en ce quil utilise : un polypeptide ayant des propriétés antigéniques envers les anticorps anti-WT1, choisi parmi un polypeptide comprenant la séquence dacides aminés des positions 294-449 de SEQ ID No : 1, un polypeptide partiel dudit polypeptide, et un polypeptide comprenant une séquence dacides aminés dont un ou plusieurs acides aminés sont délétés, substitués, ou ajoutés par rapport à la séquence dacides aminés constituant les polypeptides ci-dessus et/ou un polypeptide ayant des propriétés antigéniques envers les anticorps anti-WT1, choisi parmi un polypeptide comprenant la séquence dacides
