Abstract: The present invention relates to a kit for diagnosing non-pregnancy and a method for diagnosing non-pregnancy of an animal using the same, and more particularly, to a kit for diagnosing non-pregnancy of animal comprising: an assay strip, formed of thin film type paper comprising a plurality of holes for moving a test sample, wherein progesterone-BSA conjugate is immobilized on one end portion as a test line and anti-IgG is immobilized on the other end portion as a control line; and anti-progesterone IgG-gold conjugate for reacting with the test sample such as blood or milk. The inventive kit for diagnosing non-pregnancy can test the non-pregnancy of milch cow without any special device about 20 days after the artificial insemination. Furthermore, more accurate result can be obtained by using the kit since the non-pregnancy diagnosis is performed by comparing color of the test line with that of the control line.