Various embodiments of the present invention relate to an apparatus and method for adjusting a screen size in an electronic device. The electronic device comprises a touch screen and a processor, wherein the processor may perform control so as to: detect a touch input from a reference area set in at least a partial area of the touch screen; when it is detected that the touch input moves, activate a screen adjustment mode on the basis of a movement range of the touch input; when the touch input is maintained, adjust a screen size of the touch screen on the basis of the movement distance of the touch input; and when the touch input is released, set, as a screen size in the screen adjustment mode, the screen size at the time when the touch input is released. Other embodiments may also be possible.