An upconversion multicolor light-emitting polymer composite implements red, green, and blue colors at wavelengths in each specific region by mixing: an upconversion nanophosphor emitting light in red and blue colors at wavelengths in each specific region by absorbing the infrared light; an upconversion nanophosphor emitting light in green and blue colors at wavelengths in each specific region by absorbing the infrared light; and a polydimethylsiloxane (PDMS) polymer. Accordingly, a volumetric display with excellent color reproducibility may be realized with a simple manufacturing process.