Disclosed herein are a back light unit including a quantum dot sheet capable of recycling light converted by quantum dots, and a display apparatus including the back light unit. The back light unit according to an example includes: a light source; and a quantum dot sheet configured to convert light generated in the light source into white light, wherein the quantum dot sheet includes a fluorescent member including quantum dots; a first barrier film disposed on the rear surface of the fluorescent member; and a second barrier film disposed on the front surface of the fluorescent member, and having a predetermined reflectivity to reflect the white light converted by the fluorescent member backward toward the fluorescent member.