A thieno[3,2-b]indole-based polymer and an organo-electroluminescent device in which the polymer is introduced into an organic layer are provided. The thieno[3,2-b]indole-based polymer may be easily prepared and has blue light-emitting characteristic. The organo-electroluminescent device adopting the organic layer using the thieno[3,2-b]indole-based polymer has improved color purity, efficiency, and luminance characteristics.