To provide a polyacetal resin composition excellent in thermal stability, in spite of being colored with a pigment, and also suppressed in the amount of formaldehyde generation and mechanical strength reduction.

This polyacetal resin composition is characterized by containing 100 pts.wt. polyacetal resin, 0.01 to 5 pts.wt. coloring matter selected form inorganic and organic pigments, 0.01 to 3 pts.wt. amino group-containing siloxane compound having the physical property of having 100 to 10,000 amino equivalent, 0.01 to 1 pt.wt. dihydrazide compound selected from the group consisting of an aromatic dihydrazide compound and an aliphatic dihydrazide compound having <1 g solubility to 100 g water at 20°C and 0.01 to 1 pt.wt. sterically hindered phenol compound.