In order to facilitate creation of a controller program and a UI program in which variables match each other, this program development support unit is provided with: a calculation unit and a program development support program which implement a sequence program editing unit, a UI editing unit, and a copy function unit; a display unit; and an operation input unit. The copy function unit detects selection, through the input operation unit, of an element of the sequence program and movement to an editing screen in a user interface program, and causes elements in the user interface program that correspond to elements in the sequence program to be reflected on the editing screen of the user interface program. The copy function unit detects the type of the sequence program being edited, and, depending on the type of sequence program, determines the type of elements of the user interface program.