The present invention discloses a flat panel display capable of improving a white balance by using offset lengths or doping concentrations of offset regions between multi gates of driving transistors in R, G, and B unit pixels. The flat panel display comprises a plurality of pixels, where each of the pixels includes R, G and B unit pixels to embody red (R), green (G) and blue (B) colors, respectively, and each of the unit pixels including a transistor with multi gates. Transistors of at least two unit pixels of the R, G, and B unit pixels have offset regions with different geometric structures between the multi gates from one another. An offset region of a transistor for driving a light-emitting device having the highest luminous efficiency among the transistors of the R, G, and B unit pixels, is formed to have a longer offset length or a lower doping concentration, than those of offset regions of transistors for driving light-emitting devices having relative lower luminous efficiency.