A liquid crystal display device comprising, a liquid crystal display panel, a timing controller configured to output a light-source controlling signal during a variable frequency mode comprising a plurality of frames with variable frame frequencies, the light-source controlling signal having a high level during a light-on period preset in an early period of a frame of the plurality of frames and a low level during a light-off period preset to a length according to a frame frequency in a latter period of the frame of the plurality of frames, and a light source configured to emit light during the light-on period and not emit light during the light-off period in response to the light-source controlling signal.