A device and method of controlling a light source in eye tracking using a glint are provided. The method includes transmitting, from a processor to a first camera and a second camera, an activation signal to instruct the first and second cameras to operate according to a pattern, transmitting, to a first light driver and a second light driver, a control command to instruct the first and second light drivers to operate according to a control signal (a first control signal or a second control signal) corresponding to each of the first and second light drivers, and preventing the processor from intervening in a process of turning on and off odd-numbered light sources and even-numbered light sources.