An optical device for augmented reality having improved light transmittance, the optical device comprising: an image output unit configured to output augmented reality image light corresponding to an image for augmented reality; a reflective unit configured to transfer the augmented reality image light, output from the image output unit, to a pupil of an eye of a user by reflecting the augmented reality image light toward the pupil, thereby providing the image for augmented reality to the user; and an optical means adapted such that the reflective unit is disposed therein, and configured to transmit at least a portion of real object image light, output from a real object, therethrough toward the pupil of the eye of the user; characterized in that the reflective unit is formed to have a size of 4 mm or less and is spaced apart from the surface of the optical means and embedded and disposed inside the optical means, wherein the reflective unit is composed of an optical filter that reflects only image light belonging to a wavelength band of a specific color and transmits image light having a wavelength other than the wavelength band of the specific color therethrough, and wherein the reflective unit transfers only augmented reality image light belonging to the wavelength band of the specific color, in the augmented reality image light output from the image output unit, to the pupil of the eye of the user by reflecting the former augmented reality image light toward the pupil, and transfers the image light having a wavelength other than the wavelength band of the specific color, in the real object image light output from the real object and entering the reflective unit, to the pupil of the eye of the user by transmitting the image light toward the pupil. an image output unit configured to output augmented reality image light corresponding to an image for augmented reality; a reflective unit configured to transfer the augmented reality image light, output from the image output unit, to a pupil of an eye of a user by reflecting the augmented reality image light toward the pupil, thereby providing the image for augmented reality to the user; and an optical means adapted such that the reflective unit is disposed therein, and configured to transmit at least a portion of real object image light, output from a real object, therethrough toward the pupil of the eye of the user; characterized in that the reflective unit is formed to have a size of 4 mm or less and is spaced apart from the surface of the optical means and embedded and disposed inside the optical means, wherein the reflective unit is composed of an optical filter that reflects only image light belonging to a wavelength band of a specific color and transmits image light having a wavelength other than the wavelength band of the specific color therethrough, and wherein the reflective unit transfers only augmented reality image light belonging to the wavelength band of the specific color, in the augmented reality image light output from the image output unit, to the pupil of the eye of the user by reflecting the former augmented reality image light toward the pupil, and transfers the image light having a wavelength other than the wavelength band of the specific color, in the real object image light output from the real object and entering the reflective unit, to the pupil of the eye of the user by transmitting the image light toward the pupil.