To provide a polyoxymethylene improved in thermal stability by adding radical scavengers.

The modified polyoxymethylene improved in thermal stability by adding at least two radical scavenger components is provided; wherein, the radical scavengers are at least two compounds selected from the group consisting of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, pentaerythrityl-tetrakis[3,3,5-di-tert-butyl-4-hydroxyphenyl]propionate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, and octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate.