A polymer composition comprising 1 to 99 wt % of a copolymer (A) and 99 to 1 wt % of a copolymer (B); the polymer composition used as a light emitting material of a light emitting device having high performances; Copolymers (A) and (B) being copolymers showing fluorescence in the solid state and having a polystyrene-reduced number average molecular weight of 103 to 108, and containing a repeating unit (a) and a repeating unit (b); Copolymer (A) has a relation of 100>XaA>5, where XaA (%) is a percentage of the mol number of repeating unit (a) based on the sum of the mol numbers of repeating units (a), and Copolymer (B) satisfies a relation of XaB≦XaA−5, where XaB (%) is a percentage of the mol number of repeating unit (a) based on the sum of the mol numbers of repeating units (a) and (b).