An activity management device includes a data acquirer, an inferrer, an information acquirer, and an outputter. The data acquirer acquires in-residence data relating to a living environment of a user and acquired in a residence of the user. The inferrer infers a past or future change event in the lifestyle pattern of the user based on the in-residence data acquired by the data acquirer. The information acquirer acquires recommendation information which is information corresponding to the change event inferred by the inferrer and which prompts the user to perform an activity according to the change in the lifestyle pattern. The outputter outputs the recommendation information acquired by the information acquirer.