PURPOSE: To obtain a polyacetal resin composition, especially excellent in retention thermal stability in blending a polyacetal resin with carbon black.

CONSTITUTION: This polyacetal resin composition is obtained by adding (A) 0.01-20.0 pts.wt. acrylonitrile-based polymer and (B) 0.01-5.0 pts.wt. triazine derivative to 100 pts.wt. polyacetal resin and melt kneading the resultant mixture in blending the polyacetal resin with carbon black. Thereby, the polyacetal resin composition, especially excellent in retention thermal stability can be obtained in molding such as injection molding when a polyacetal product for the purpose of imparting coloring or electric conductivity, improving the weather resistance, etc., is produced.