a data processing apparatus includes a key input device , a display device , a schedule data memory for storing schedule data attached with a data and a time within the date inputted from the key input device by the day , a time calculator for calculating a present date and time based on a date and time initially set , an alarm setting device for setting a requisition of alarm in a schedule data of a desired data and time included in the schedule data stored in the schedule data memory , a comparator for comparing the present date and time outputted from the time calculator with the date and time attached to the schedule data set with the requisition of the alarm by the alarm setting device and a display controller for simultaneously displaying the schedule data set with the requisition of the alarm and other schedule data being adjacent to said schedule data when the result of the comparison by the comparator is conformable .