A liquid crystal display device includes a plurality of pixel units. Each of the pixel units includes a first thin film transistor and a second thin film transistor, a reflective sheet, and a storage capacitor. The channel width/length ratio of the first thin film transistor and the channel width/length ratio of the second thin film transistor are both larger than 12/5. The reflective sheet is disposed adjacent to the first thin film transistor and the second thin film transistor to reflect ambient light. The storage capacitor is formed at a position overlapping the reflective sheet and has a capacitance of larger than 1 pF.