A backlight unit comprising: a light guiding layer including an incident surface on which light is incident and an exit surface (LGL-T) from which light is emitted; a light source disposed on the incident surface of the light guiding layer and configured to generate the light; a low refraction layer disposed on the exit surface (LGL-T) of the light guiding layer; a color control layer disposed on the low refraction layer; and a protection layer disposed on the color control layer characterized in that a refractive index of the low refraction layer is lower than a refractive index of the light guiding layer and a refractive index of the color control layer; wherein the difference in refractive index between the low refraction layer and the light guiding layer is at least 0.2, the protection layer includes a resin composition including a first repeating unit represented by Formula 1 below: in Formula 1, R 1 and R 2 are each independently selected from a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amine group, a substituted or unsubstituted epoxy group, a substituted or unsubstituted thiol group, a substituted or unsubstituted acrylic group, a substituted or unsubstituted methacrylic group, a substituted or unsubstituted isocyanate group, a nitrile group, a nitro group, a substituted or unsubstituted alkyl group having 1 to 10 carbons, a substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 ring-forming carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 12 ring-forming carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 ring-forming carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted aryl thiol group having 6 to 30 ring-forming carbon atoms; and wherein the protection layer is disposed in an outermost region of the backlight unit. a light guiding layer including an incident surface on which light is incident and an exit surface (LGL-T) from which light is emitted; a light source disposed on the incident surface of the light guiding layer and configured to generate the light; a low refraction layer disposed on the exit surface (LGL-T) of the light guiding layer; a color control layer disposed on the low refraction layer; and a protection layer disposed on the color control layer characterized in that a refractive index of the low refraction layer is lower than a refractive index of the light guiding layer and a refractive index of the color control layer; wherein the difference in refractive index between the low refraction layer and the light guiding layer is at least 0.2, the protection layer includes a resin composition including a first repeating unit represented by Formula 1 below: in Formula 1, R 1 and R 2 are each independently selected from a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amine group, a substituted or unsubstituted epoxy group, a substituted or unsubstituted thiol group, a substituted or unsubstituted acrylic group, a substituted or unsubstituted methacrylic group, a substituted or unsubstituted isocyanate group, a nitrile group, a nitro group, a substituted or unsubstituted alkyl group having 1 to 10 carbons, a substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 ring-forming carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 12 ring-forming carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 ring-forming carbon atoms, a substituted or unsubstituted aralkyl group having 6 to 30 ring-forming carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 ring-forming carbon atoms, or a substituted or unsubstituted aryl thiol group having 6 to 30 ring-forming carbon atoms; and wherein the protection layer is disposed in an outermost region of the backlight unit.