In an electron gun assembly, three eletron beams emitted from cathodes (KR, KG, KB) are passed through an electrode arrangement (10, 60, 90) in which two inter­mediate electrodes (70, 80) are arranged between focus­ing are accelerating electrodes (50, 60). A focusing voltage which is varied depending on an deflection of the electron beam is applied to the focusing electrode (50) and an accelerating voltage is applied to the acce­lerating electrode (60). A resistor (100) is connected between the accelerating electrode (60) and the earth through a variable resistor (105) and intermediate points of the reisistor (100) are connected to the intermediate electrodes (50, 60). Thus, convergent and divergent lenses (200, 210, 300, 310) are formed between the focusing electrode (50) and the intermediate elec­trode (70) and between the accelerating electrode (60) and the intermediate electrode (80). The lens powers of the convergent and divergent lenses (200, 210, 300, 310) are varied in accordance with the adjustment of the variable resistor (105).