An apparatus and method for driving a liquid crystal display (LCD) device is disclosed. The apparatus for driving a liquid crystal display (LCD) device includes a liquid crystal display (LCD) panel for receiving a video signal and a clock signal, and displaying them, a backlight for emitting light on the LCD panel, a timing controller for controlling the LCD panel and the backlight, a signal generator which has the same frequency as that of a horizontal synchronous signal by modulating the clock signal, and generates a signal synchronized with the horizontal synchronous signal, and an inverter which receives a signal from the signal generator, allows a driving frequency of the light source to be the same as that of the horizontal synchronous signal, and allows the received signal to be synchronized with the horizontal synchronous signal.