Abstract: A focus unit of an FBT (fly back transformer) is described, which is installed on a side of the FBT, for adjusting the focus and screen voltages of a cathode ray tube. Focus and screen voltage adjusting round resistor patterns 130 are respectively formed on volume boards 120 of the focus unit, and a supporting shaft 160 is received into a central through hole 140 of the round resistor pattern 120. A connecting pin 170 is inserted into the supporting shaft 160, and a cable 210 is inserted into each of holes of a volume case so as for the cable to be connected to the lower end of the connecting pin 170. A pair of actuation knobs are inserted into a cover, and a slider spring is installed within each of volume bars, while the lower end of the slider spring 230 is movably connected to the round resistor pattern 130. Thus the slider spring for adjusting the focus volume can be easily installed on a volume bar, and the focus and screen voltages can be controlled in a sure manner.