A polarizing plastic lens comprising a polarizing film with low tendency to detachment from an optical resin layer. There is provided polarizing plastic lens comprising polarizing film constituted of a polyvinyl alcohol resin. Two optical resin layers of different thicknesses may be disposed on both surfaces of the polarizing film. The optical resin layers are formed by polymerizing a polymerization raw material composition in contact with the polarizing film. The polymerization raw material composition contains as one main component an isocyanated or isothiocyanated compound. The iscocyanate or isothiocyanate functional group reacts with the hydroxyl of polyvinyl alcohol resin of polarizing film to thereby form an urethane bond or thiourethane bond, so that the optical resin layers are strongly unified with the polarizing film.