A backlight assembly comprising: a receiving container having a bottom plate and a side wall defining a receiving space; a diffusion plate disposed over the receiving space; a light source unit disposed in the receiving space and comprising a circuit board on which a plurality of point light sources are mounted in a line, wherein the point light sources are oriented to emit light mainly in a direction parallel to a plane of the diffusion plate; and a reflective element having a reflective surface which forms a predetermined angle greater than 0 degree with respect to the bottom plate and is oriented to reflect the light from the point light source of an adjacent light source unit toward the diffusion plate, the reflective surface being disposed on the circuit board and along rear surfaces of the point light sources and separated from the point light sources by a predetermined distance (d), wherein each point light source comprises a light-emitting diode chip; each point light source further comprises: a heat dissipating part adjacent to the LED chip to dissipate heat generated from the LED chip; characterized in that a housing adhered to the circuit board receiveing the LED chip and the heat dissipating part, and a heat blocking layer formed between the heat dissipating part and the housing to block heat conduction, wherein the heat blocking layer is formed in an area that excludes the area adjacent to and facing the circuit board. a receiving container having a bottom plate and a side wall defining a receiving space; a diffusion plate disposed over the receiving space; a light source unit disposed in the receiving space and comprising a circuit board on which a plurality of point light sources are mounted in a line, wherein the point light sources are oriented to emit light mainly in a direction parallel to a plane of the diffusion plate; and a reflective element having a reflective surface which forms a predetermined angle greater than 0 degree with respect to the bottom plate and is oriented to reflect the light from the point light source of an adjacent light source unit toward the diffusion plate, the reflective surface being disposed on the circuit board and along rear surfaces of the point light sources and separated from the point light sources by a predetermined distance (d), wherein each point light source comprises a light-emitting diode chip; each point light source further comprises: a heat dissipating part adjacent to the LED chip to dissipate heat generated from the LED chip; characterized in that a housing adhered to the circuit board receiveing the LED chip and the heat dissipating part, and a heat blocking layer formed between the heat dissipating part and the housing to block heat conduction, wherein the heat blocking layer is formed in an area that excludes the area adjacent to and facing the circuit board. a heat dissipating part adjacent to the LED chip to dissipate heat generated from the LED chip; characterized in that a housing adhered to the circuit board receiveing the LED chip and the heat dissipating part, and a heat blocking layer formed between the heat dissipating part and the housing to block heat conduction, wherein the heat blocking layer is formed in an area that excludes the area adjacent to and facing the circuit board.