In one embodiment of the present invention, a display controller includes a stable pixel writing period in one horizontal period in a display device, the stable pixel writing period being a period during which a voltage outputted from a gate driver is at a high level. The display controller also includes a first stable pixel writing period determination circuit which determines, by using a reference signal independent from the frame rate in the display device, the stable pixel writing period during which the voltage is at the high level. Thus, the display controller can be provided in which, regardless of whether and how the frame rate is changed, the stable pixel writing period can be of a target length.