We study exotic mesons with double charm and bottom flavor (), whose quark configuration is . This quark configuration has no annihilation process of quark and antiquark, and hence is a genuinely exotic state. We take a hadronic picture by considering the molecular states composed of a pair of heavy mesons, such as DD, , and for charm flavor, and BB, , and for bottom flavor. The interactions between heavy mesons are derived from the heavy quark effective theory. All molecular states are classified by quantum numbers, and are systematically studied up to the total angular momentum . By solving the coupled channel Schrödinger equations, due to the strong tensor force of one-pion exchange, we find bound and/or resonant states of various quantum numbers.