System construction assist device, method, and recording medium

In order to increase user convenience, a system construction assist device is provided with: a first display screen; a second display screen; and a processing unit that sorts a plurality of units each belonging to any of a plurality of categories according to category and displays the units on the first display screen, that receives a first input for selecting one unit from the plurality of units displayed on the first display screen, that generates a system configuration diagram on the basis of the received first input, and that displays the generated system configuration diagram on the second display screen. The processing unit, after newly receiving the first input (S1) and before receiving the next first input, estimates the category to which the unit selected by the next first input belongs on the basis of a plurality of first inputs that have been received in the past (S5 to S8), and presents the estimated category to a user as a candidate category (S9).