NOVELTY - A conjugated polymer containing nitrogen-containing repeating unit (I) is new. The conjugated polymer contains insolubilization group as substituent, and has weight average molecular weight of 20000 or more and dispersion degree of 2.4 or less.    USE - Conjugated polymer is used for organic electroluminescent element material, composition for organic electroluminescent element used for organic electroluminescent display and organic electroluminescent illumination device (all claimed), light source of copier, back light source of liquid crystal display and measuring instrument, display board and marker lamp, flat panel display for office automated computer and wall-mounted television. Can also be used for electrophotographic photoreceptor, photoelectric transducer, organic solar cell and organic rectifier.    ADVANTAGE - The conjugated polymer has high hole transport ability, solubility with respect to solvent, and improved surface flatness during film-forming method. The conjugated polymer provides organic electroluminescent element having high luminous efficiency, heat resistance and drive durability.    DETAILED DESCRIPTION - A conjugated polymer containing nitrogen-containing repeating unit of formula: -(Ar11-N(-Ar13)-(Ar14-N(-Ar15))m-Ar12)- (I) is new. The conjugated polymer contains insolubilization group as substituent, and has weight average molecular weight of 20000 or more and dispersion degree of 2.4 or less.    Ar11,Ar12=direct bond, optionally substituted aromatic hydrocarbyl or optionally substituted aromatic heterocyclic group;    Ar13-Ar15=aromatic hydrocarbyl or aromatic heterocyclic group (both optionally having substituent);and    m=0-3.    INDEPENDENT CLAIMS are included for the following:    (1) composition, which contains conjugated polymer;    (2) organic electro luminescent element, which has organic layer(s) having insolubilization polymer obtained by insolubilizing conjugated polymer, provided between anode and cathode on substrate; and    (3) manufacture of polymer (A).