A liquid crystal display device comprising: a liquid crystal display panel and a back-light unit, wherein the back-light unit includes a plurality of adjacent light guide portions (100A 1-2) and a frame, wherein each of the light guide portions includes: a light guide plate having a light input part and a first connection part; a reflection plate on an underside of, and coupled to, the light guide plate, the reflection plate having a second connection part connected to the first connection part; and a light source including at least one light emitting diode, the light source emitting light toward the light guide portion, wherein light from the light source is incident to the light input part of the light guide plate; wherein each of the light guide portions includes a third connection part and the frame includes a fourth connection part, wherein the third connection part is configured to couple with the fourth connection part, wherein the third connection part includes a hook (167a, 167b) and the fourth connection part includes an opening (166a, 166b), and wherein the hook is configured, at least in part, to pass through the opening; wherein a first light guide portion (100A 1) and an adjacent second light guide portion (100A 2) are coupled such that the light input part of the second light guide portion (100A 2) is covered by the other edge of the first light guide portion (100A 1) opposite the light input part of the first light guide portion (100A 1), the other edge having attached to its underside the reflection plate of the first light guide portion (100A 1); wherein the reflection plate on the underside of the other edge of the first light guide portion (100A 1) and an edge of the reflection plate extended therefrom optically shield a portion of the light guide plate of the first light guide portion (100A 1) from light transmission from the second light guide portion (100A 2) to the first light guide portion (100A 1) and vice versa. a liquid crystal display panel and a back-light unit, wherein the back-light unit includes a plurality of adjacent light guide portions (100A 1-2) and a frame, wherein each of the light guide portions includes: a light guide plate having a light input part and a first connection part; a reflection plate on an underside of, and coupled to, the light guide plate, the reflection plate having a second connection part connected to the first connection part; and a light source including at least one light emitting diode, the light source emitting light toward the light guide portion, wherein light from the light source is incident to the light input part of the light guide plate; wherein each of the light guide portions includes a third connection part and the frame includes a fourth connection part, wherein the third connection part is configured to couple with the fourth connection part, wherein the third connection part includes a hook (167a, 167b) and the fourth connection part includes an opening (166a, 166b), and wherein the hook is configured, at least in part, to pass through the opening; wherein a first light guide portion (100A 1) and an adjacent second light guide portion (100A 2) are coupled such that the light input part of the second light guide portion (100A 2) is covered by the other edge of the first light guide portion (100A 1) opposite the light input part of the first light guide portion (100A 1), the other edge having attached to its underside the reflection plate of the first light guide portion (100A 1); wherein the reflection plate on the underside of the other edge of the first light guide portion (100A 1) and an edge of the reflection plate extended therefrom optically shield a portion of the light guide plate of the first light guide portion (100A 1) from light transmission from the second light guide portion (100A 2) to the first light guide portion (100A 1) and vice versa. a light guide plate having a light input part and a first connection part; a reflection plate on an underside of, and coupled to, the light guide plate, the reflection plate having a second connection part connected to the first connection part; and a light source including at least one light emitting diode, the light source emitting light toward the light guide portion, wherein light from the light source is incident to the light input part of the light guide plate; wherein each of the light guide portions includes a third connection part and the frame includes a fourth connection part, wherein the third connection part is configured to couple with the fourth connection part, wherein the third connection part includes a hook (167a, 167b) and the fourth connection part includes an opening (166a, 166b), and wherein the hook is configured, at least in part, to pass through the opening; wherein a first light guide portion (100A 1) and an adjacent second light guide portion (100A 2) are coupled such that the light input part of the second light guide portion (100A 2) is covered by the other edge of the first light guide portion (100A 1) opposite the light input part of the first light guide portion (100A 1), the other edge having attached to its underside the reflection plate of the first light guide portion (100A 1); wherein the reflection plate on the underside of the other edge of the first light guide portion (100A 1) and an edge of the reflection plate extended therefrom optically shield a portion of the light guide plate of the first light guide portion (100A 1) from light transmission from the second light guide portion (100A 2) to the first light guide portion (100A 1) and vice versa.