Abstract: A polyoxymethylene copolymer which is a polyoxymethylene copolymer obtained by copolymerizing trioxane and 8 to 20 mol, per 100 mol of the trioxane, of 1,3-dioxolane and which (i) has a crystallization time period of 10 to 2,000 seconds at 143° C., (ii) withstands 30 to 1,000 cycles of a bending durability test and (iii) has residence heat stability for 40 minutes or more, and a molded article formed of the copolymer. According to the present invention, there can be provided a polyoxymethylene copolymer excellent in bending durability and heat stability and excellent in moldability, and a molded article formed thereof.