Provided is a long-fiber-reinforced thermoplastic resin preform including glass fibers excellent in strength and modulus of elasticity and easily produced and a long-fiber-reinforced resin compact excellent in strength and modulus of elasticity. The long-fiber-reinforced thermoplastic resin preform is produced by cutting to a predetermined length glass fiber bundles impregnated with a thermoplastic resin and holding the thermoplastic resin around the glass fiber bundles, and includes the glass fiber bundles as long fiber bundles. The glass fiber bundles are formed by bundling glass fibers. The glass fibers have a composition wherein the content of SiO 2 is 57.0 to 63.0% by mass, the content of Al 2 O 3 is 19.0 to 23.0% by mass, the content of MgO is 10.0 to 15.0% by mass and the content of CaO is 5.5 to 11.0% by mass, and the ratio MgO/CaO is 0.8 to 2.0.