substance contained in sample which has inevitably caused nonspecific agglutination reaction according to the prior art application_number US 60152284 A description antibody to be used in the invention is prepared immunologically by applying the so called high molecular weight antigens such as proteins polypeptides polysaccharides lipids which form antigen antibody reaction precipitate when reacted with antigen or the so called low molecular weight antigens haptens such as steroids haptenes for medicines which do not form precipitate although antigen antibody reaction occurs to a mammal such as guinea pig rabbit goat sheep and equine among which rabbit goat and sheep are more preferable according to the usual method there is no particular limitation in the kind of antigen antibody is obtained as antiserum containing antibody specific to respective antigen such antiserum may be used in the invention as it is since animal serum contains various substances having biological activity immunoglobulin containing antibody may be separated according to the usual method from said antiserum or specific antibody itself may be obtained according to the usual purification method to be used for the invention various methods have been established for separation of immunoglobulin among which method of ammonium sulfate precipitation deae cellulose column chromatography and combination thereof are usual at the present as for purification affinity chromatography is usually used.