A surface light source device for illuminating a transmission-type liquid crystal display unit from a back surface, the liquid crystal display unit having a display area including pixels arranged in a two-dimensional matrix, the surface light source device comprising: P×Q rectangular surface light source units corresponding to P×Q imaginary display area units obtained by assuming that the display area of the liquid crystal display unit is divided into the P×Q imaginary display area units, wherein each surface light source unit is individually controlled and includes a plurality of light-emitting units, each of said light emitting units being arranged at one of the four corners of an imaginary rectangle with sides parallel to the sides of the surface light source unit and including at least one red light-emitting element that emits red light, at least one green light-emitting element that emits green light, and at least one blue light-emitting element that emits blue light, the surface light source unit being thereby adapted to emit white light, characterised in that the red, green and blue light-emitting elements (44R, 44G, 44B) constituting the plurality of light-emitting elements in each of the surface light source units are arranged four-rotation symmetrically so that the centre of mass of the luminance profile based on the plurality of red light-emitting elements in each of the surface light source units, the centre of mass of the luminance profile based on the plurality of green light-emitting elements in each of the surface light source units, and the centre of mass of the luminance profile based on the plurality of blue light-emitting elements in each of the surface light source units each substantially coincide with the centre of mass of the light source unit. P×Q rectangular surface light source units corresponding to P×Q imaginary display area units obtained by assuming that the display area of the liquid crystal display unit is divided into the P×Q imaginary display area units, wherein each surface light source unit is individually controlled and includes a plurality of light-emitting units, each of said light emitting units being arranged at one of the four corners of an imaginary rectangle with sides parallel to the sides of the surface light source unit and including at least one red light-emitting element that emits red light, at least one green light-emitting element that emits green light, and at least one blue light-emitting element that emits blue light, the surface light source unit being thereby adapted to emit white light, characterised in that the red, green and blue light-emitting elements (44R, 44G, 44B) constituting the plurality of light-emitting elements in each of the surface light source units are arranged four-rotation symmetrically so that the centre of mass of the luminance profile based on the plurality of red light-emitting elements in each of the surface light source units, the centre of mass of the luminance profile based on the plurality of green light-emitting elements in each of the surface light source units, and the centre of mass of the luminance profile based on the plurality of blue light-emitting elements in each of the surface light source units each substantially coincide with the centre of mass of the light source unit.