Organic light-emitting display apparatus including nano-structured mirror

An OLED apparatus includes a plurality of blue pixels configured to emit blue light, a plurality of green pixels configured to emit green light, and a plurality of red pixels configured to emit red light. Each of the plurality of blue, green, and red pixels includes a reflection layer; a first electrode arranged on the reflection layer; a light-emitting region arranged on the first electrode; and a second electrode arranged on the light-emitting region. An upper surface of the reflection layer of the blue pixel is continuously flat, and an upper surface of the reflection layer of the green pixel and an upper surface of the reflection layer of the red pixel are level with each other. Each of the green pixel or each of the red pixel includes a plurality of nano-structures protruding from a bottom surface of the reflection layer to the upper surface of the reflection layer.