||The conjugated polymer-based fluorescent sensors have received attention as the active materials in chemosensors, Because the conjugated polymer-based fluorescent sensors have higher sensitivity than small molecules of prove via FRET between fluorescent prove and conjugated polymer. We choose the rhodamine 6G derivative as a fluorescent prove for using sensor. The rhodamine 6G derivative have the spirolactam moiety. When a metal ions bind on spirolactam moiety, the moiety is changed to ring-opened amide form gives pink color and strong fluorescence. Herein, we prepared conjugated polymer containing rhodamine 6G derivative as a side chain by a Suzuki coupling reaction. When an Al3+ bound to rhodamine 6G derivatives in polymer by ligand interactions, the rhodamine 6G derivative showed absorption and red emission. As a result, the red emission of rhodamine 6G was increased and the emission of polymer was decreased upon excitation of the polymer via FRET.