#$%^&*AU2008202992B220120329.pdf#####ABSTRACT It is intended to provide an antibody showing immunoreactivity selectively to ADAMTS-13 and applications of this antibody in epitope analysis or diagnosis of an ADAMTS-13 autoantibody-positive patient. Alternatively, it is intended to provide a process for producing and use of a modified ADAMTS-13 molecule partially deleted aiming at the application in pharmaceutical products. An antibody specific for ADAMTS-13 which can be obtained from a warm-blooded animal immunized and sensitized with a polypeptide containing a part or the whole of ADAMTS-13 amino acid sequence; a process for producing an antibody comprising a step of immunizing and sensitizing a warm-blooded animal with a polypeptide containing a part or the whole of ADAMTS-13 amino acid sequence; use of the above-described antibody including a method of detecting and purifying ADAMTS-13; and a modified ADAMTS-13 molecule partially deleted are provided.