A data management device selects acquisition data of a deletion target from a storage device storing multiple acquisition data acquired by a board work machine performing a predetermined board work on a board. The data management device includes an acquisition section and a selection section. The acquisition section divides an evaluation index when evaluating a target object extracted from the acquisition data or the board work using the target object into multiple classes and acquires frequency-related information obtained by calculating a frequency of the acquisition data belonging to each of the classes for the multiple acquisition data of the same type stored in the storage device. The selection section selects the acquisition data having a higher frequency as the acquisition data of the deletion target by using the frequency-related information acquired by the acquisition section.