Protein having antithrombotic activity and method for producing the same

A method for producing a protein having an antithrombotic activity, which comprises replacing, in a protein that has an amino acid sequence having a homology of not.less than 30% to the amino acid sequence of SEQ ID NO: 1 and forms a higher order structure composed of a first strand ( 1), a first a helix ( 1), a second helix ( 2), a second strand ( 2), a loop, a third strand ( 3), a fourth strand ( 4) and a fifth strand ( 5) in this order from the amino terminus, at least one amino acid residue in a region from 2 to 2 and/or a region from 3 to 4 so that electric charge of the amino acid residue is changed towards positive direction.