Thermoplastic resin molded body and manufacturing method thereof, thermoplastic resin light guide, light source device and liquid crystal display device

[Problem] To provide a thermoplastic resin molded body in which a vacancy is formed having excellent light emission efficiency, and a thermoplastic resin light guide using same. [Solution] In a state focused on the interior of a thermoplastic resin molding element, a pulse laser is irradiated to form a crack in the interior of the thermoplastic resin molding element; thereafter, the thermoplastic resin molding element is heat-treated at no less than the glass transition temperature of the thermoplastic resin configuring the thermoplastic resin molding element, thereby obtaining a thermoplastic resin molded body (20) having an approximately spherical vacancy (244) with a minimum diameter of 30μm or greater only in the interior 10μm or more from the surface.