To provide a method for producing a glass fiber-reinforced polyamide resin composition high in productivity and excellent in strength and rigidity, especially when the composition is exposed to high temperatures and the composition.

In the method for producing the polyamide resin composition which is produced by melt-kneading the polyamide resin and roving of continuous glass fibers by a twin-screw extruder, the length of the glass fibers in the composition is controlled under specified melt-kneading conditions.