To provide a polyacetal resin composition that excels in hydrolysis resistance and a mold deposit property when being formed, and in which when being formed to a molding having a welded part, the generation of a crack in the welded part can be controlled sufficiently.

The polyacetal resin composition to form a molding having a welded part, includes: 10-85 parts by mass of a polylactic acid resin (B) based on 100 parts by mass of a polyacetal resin (A); and at least 0.05 part by mass and less than 0.90 part by mass of a carbonyl terminal blocking agent (C) based on 100 parts by mass of the total of the polyacetal resin (A) and the polylactic acid resin (B), wherein the polyacetal resin (A) contains an oxymethylene group and a 2-6C oxyalkylene group, and the proportion of the oxyalkylene group that occupies in the total molar number of the oxymethylene group and the oxyalkylene group is 0.5-10 mole%.