The present invention provides an antibody capable of specifically recognizing and detecting the highly specific cancer marker with respect to the epithelial ovarian cancer, or a fragment of the antibody. The present invention provides an anti-²1,3-N-acetylglucosaminyltransferase 3 antibody for diagnosis of epithelial ovarian cancer, i.e., an antibody for detection of a glycosyltransferase ²1,3-N-acetylglucosaminyltransferase 3 as an epithelial ovarian cancer marker. The antibody recognizes, as an epitope, a part of a polypeptide of the enzyme consisting of the amino acid sequence represented by SEQ ID NO: 1.