The present invention relates to a protein containing a modified DDR (Discoidin Domain Receptor) 2 cytosolic tyrosine kinase domain having an increased autophosphorylation and tyrosine kinase activity; a method for preparing a large amount of a protein containing DDR2 cytosolic tyrosine kinase domain, having an increased autophosphorylation and tyrosine kinase activity by inducing phosphorylations of tyrosines by a co-expression with Src or Src related proteins in host cells, or by H2O2 processing of host cells, or a site directed mutation modifying at least one of tyrosines to other amino acid; and a use thereof as a target material in developing medical drugs for treating a disease caused by an excessively activated DDR2 autophosphorylation and tyrosine kinase activity.