We measured NMR and ESR in solid state of a Br2 doped halogen-bridged one-dimensional mixed-valence complex, {[Pt(en)2][PtBr2(en)2]}3(CuBr4)4.12H2O, which forms a double chain structure consisting of -Pt(II)-Br-Pt(IV)-Br- and -Cu(I)-Br-Cu(I)-Br-. 13C NMR measurements gave broad spectra explainable by marked effects from paramagnetic sites assignable to Pt(III) and/ or Cu(II) in the chain oxidized by bromine. Pt(III) sites are considered to form neutral solitons by referring to the electrical conductivity result.