To provide a polyacetal copolymer excellent in toughness and suitable for non-injection molded article.

The polyacetal copolymer is produced by copolymerizing (A) 100 pts.wt. of a trioxane, (B) 0.1-30 pts.wt. of a cyclic ether compound copolymerizable with the trioxane and (C) 0.005-50 pts.wt. of at least one compound selected from monofunctional and/or polyfunctional cyclic siloxane compounds represented by general formula -[-SiO(R1)(R2)-]-n, (wherein, R1 and R2 are the same or different and are each a 1-20C hydrocarbon group; and n is an integer of 3-20).