Abstract: In a display device, parameters for adjusting a video circuit are previously made to correspond to application softwares, respectively and a control section for determining an application software and adjusting the video circuit by means of the parameters are provided. Since the image quality of the display device can be automatically changed over to a suitable image quality according to a selected application software, a burden on the user is extremely small, and the image quality of the display device can be adjusted according to the application software extremely easily.