A fraction collector control device includes a peak designation part that displays a chromatogram for setting and requires a user to select at least one peak in the chromatogram for setting, a parameter extraction part that extracts, as a parameter, a signal level and/or a slope at a start point and an end point of each peak designated by a user, and a threshold candidate generation part that generates, based on the parameter extracted by the parameter extraction part, a threshold candidate usable as a common threshold for detecting start points of all peaks designated by a user and a common threshold for detecting end points of all peaks designated by a user.