The present invention provides a data processing device connected with an intermission driving. The data processing device achieves a satisfactory power saving while ensuring a high level of display quality of the display device. Upon detection of non-data update in a frame buffer, the host calculates a next refreshing timing based on driving information obtained from a liquid crystal display device (LCD), sets a timer for a timeout after a length of time representing the calculated result, and then the host and the LCD shift to Intermission State 1. Thereafter, when the timer times out to bring the host back to Normal State and a data update at the frame buffer is detected, data for refreshing an display image in the LCD is transferred from the host to the LCD. If the amount of time representing the calculated result is longer than a predetermined baseline, a shift is made to Intermission State 2 which provides greater power saving than Intermission State 1.