To provide a synthetic resin application core for applying liquid cosmetics which has favorable features in sticking, sliding, and fitting to the skin and the lips as application surfaces, and which is capable of reducing stimulus, smoothing the application.

This synthetic fiber application core is composed of a porous fiber bundle body bound by a heat process and resin binder, and the resin binder is formed of polyurethane resin as a reaction product of polyisocyanate formed by adding polyfunctional alcohol to hexamethylene diisocyanate, and polyol, thereby a stimulus property to the skin and the lips is lowered.