According to one embodiment, a display device includes a display pixel allocated at a matrix state in a display area, an image-reading device which detects strength of capacitive coupling by a dielectric material coming close to or making contact with the display area, and a control portion which controls each transistor of the image-reading device. The image-reading device includes a detection electrode which forms capacitance between the detection electrode and the dielectric material, a pre-charge gate line, a coupling pulse line, a readout gate line, a pre-charge line and a readout line. These lines supply a signal which drives the image-reading device. The image-reading device further includes a pre-charge transistor, an amplification transistor, a readout transistor, a compensation transistor, and a power-source switching transistor.