To provide a polyethylene naphthalate resin composition efficiently exhibiting hydrolytic resistance with a carbodiimide compound and suppressing even degradation of the carbodiimide compound itself and to provide a method for producing the composition.

The polyethylene naphthalate resin composition comprises 0.1-10 wt.% of the carbodiimide compound and 0.05-1 wt.% of at least one kind of antioxidant selected from the group consisting of a hindered phenolic compound and a thioethereal compound. The method for producing the resin composition comprises adding the carbodiimide compound to the polyethylene naphthalate resin composition comprising the antioxidant.