An organic light-emitting device includes a first electrode layer; a hole injection layer on the first electrode layer; a hole transport layer on the hole injection layer; an electron blocking layer on the hole transport layer, and including a plurality of layers; a light-emitting layer on the electron blocking layer; an electron transport layer on the light-emitting layer; an electron injection layer on the electron transport layer; and a second electrode layer on the electron transport layer, wherein the electron blocking layer has a highest occupied molecular orbital value which is lower than a highest occupied molecular orbital value of the hole transport layer, and the light-emitting layer has a HOMO value which is lower than a highest occupied molecular orbital value of the electron blocking layer.