The object of the present invention is to provide a highly crystalline polyethylene-2,6-naphthalate composition by achieving high molecular weight of PEN, wherein the polyethylene-2,6-naphthalate composition has greatly improved blow moldability and provides molded products having excellent hue, excellent weathering resistance, and additionally excellent transparency. The above-mentioned problems can be solved by a polyethylene-2,6-naphthalate composition comprising a specific phosphoric acid which is a phosphorus compound, cobalt element derived from a cobalt compound, manganese element derived from a manganese compound, and antimony element derived from an antimony compound, wherein the content of each of the elements simultaneously satisfies the following expressions (1) to (4): 10 ‰¤ Co ‰¤ 30 mmol % 0.50 ‰¤ P / Mn ‰¤ 1.28 10 ‰¤ Sb ‰¤ 25 mmol % 0.60 ‰¤ IV ‰¤ 1.50 dL / g
