A unit pixel including a first light emitting stack; a second light emitting stack disposed under the first light emitting stack, and having an area greater than that of the first light emitting stack; a third light emitting stack disposed under the second light emitting stack, and having an area greater than that of the second light emitting stack, in which at least one of the first through third light emitting stacks includes a side surface having an inclination angle within a range of about 30 degrees to about 70 degrees with respect to a first plane parallel to a top surface of the third light emitting stack.