To provide a polyester tire cap ply cord having a high modulus of elasticity and extremely improved in heat-resistant adhesion and retention of strength, when exposed to a high temperature for a long time in rubber, and to provide a method for producing the same.

This method for producing the polyester tire cap ply cord comprises treating a polyester fiber material through single-stage, double-stage, or multi-stage treatment, by combining four components of (A) a treating liquid containing a carrier, (B) an aqueous blocked isocyanate solution, (C) a dispersion of an epoxy compound, and (D) a resorcinol-formaldehyde-latex (RFL) mixed liquid as treating liquids, in case of furnishing the polyester fiber material with adhesion to the rubber, wherein the polyester fiber material is treated with a first treating liquid into which at least (A) the treating liquid containing the carrier is mixed, then treated with a second treating liquid into which at least (D) the RFL mixed liquid is mixed, and further heat-treated under a normalizing tension controlled to be 0.2 cN/dtex or more, after treated with the second treating liquid in a final stage.