To collectively retrieve and display only schedule data on a desired project in a data display device which manages and displays inputted schedule data, for example.

Project names to which respective schedules belong are added to individual schedule data registered in a schedule data register 14c in RAM 14 so as to store them. The 'retrieval' key 12g of a key input part 12 is operated and a retrieval menu screen is displayed on a liquid crystal display part 16. When the desired project name 'A' is inputted and designated as a 'retrieval word' and 'project retrieval' is selected as a retrieval method, only schedule data 'project meeting' 'decision meeting' and 'meeting' which are registered in the schedule data register 14c and to which the project name 'A' is added are read, and they are displayed on the liquid crystal display part 16 as a list display screen.