Abstract : By considering the electron interactions in polyacetylene, it is found that there exist two gap states in charged solitons of trans- polyacetylene: one is deep level, and the other is shallow level. The deep one shifts 0.23 eV down (for a positive soliton) or up (for a negative soliton) from the center of the gap, while the shallow one is 0.06 eV under the bottom edge of the conduction band (positive soliton) or above the top edge of the valence band (negative soliton). These results agree with the absorption spectra of trans- polyacetylene. Other shallow states outside the energy bands are also predicted. Keywords: Polyacetylene; Polymers; Gap states; Charged solitons; Deep and shallow levels; Conduction and valence bands; Absorption spectra.