A display device and a projection type display device, able to realize an image display having a high precision regardless of the scanning direction of operation without a change of a phase of an output potential change, receiving a horizontal start pulse and a switch signal at a first scanning operation to sample a clock different from a clock sampled by a first shift stage of a horizontal scanner by a selector portion of a monitor circuit, setting a potential of a pulled up monitor line at a ground potential in response to this sample-and-hold pulse, receiving the horizontal start pulse and the switch signal to sample a clock different from the clock sampled by a fourth shift stage of the horizontal scanner by the selector portion of the monitor circuit at the second scanning operation, and setting the potential of the pulled up monitor line at the ground potential in response to this sample-and-hold pulse.