To provide a resin composition excellent in mechanical strength including a real use, heat resistance, and moist heat resistance by a cross-linked poly lactic acid resin, and to provide a molding in which a real use is possible.

The polylactic acid-based resin composition includes: 0.01-10 pts.mass of a carbodiimide compound based on 100 pts.mass of the total amount of 70-99 pts.mass of a polylactic acid resin in which the D-form content is at most 1.0 mole% or at least 99.0 mole% and which is crosslinked, and 30-1 pts.mass of an aramid fiber and/or an LCP fiber.