It is an object to provide a semiconductor display device having a touch panel, which can reduce power consumption. The semiconductor display device includes a panel which is provided with a pixel portion and a driver circuit which controls an input of the image signal to the pixel portion, and a touch panel provided in a position overlapping with the panel in the pixel portion. The pixel portion includes a display element configured to perform display in accordance with voltage of the image signal to be input, and a transistor configured to control retention of the voltage. The transistor includes an oxide semiconductor in a channel formation region. The driving frequency of the driver circuit, that is, the number of writing operations of the image signal for a certain period is changed in accordance with an operation signal from a touch panel.