[Problem to be Solved] There is provided a novel compound that inhibits interaction between murine double minute 2 (Mdm2) protein and p53 protein and exhibits anti-tumor activity. [Solution] The present invention provides an imidazothiazole derivative represented by the following formula (1) having various substituents that inhibits interaction between Mdm2 protein and p53 protein and exhibits anti-tumor activity: wherein R 1 R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , Ar 1 , and Ar 2 in formula (1) respectively have the same meanings as defined in the specification.
