A prediction device according to an embodiment includes one or more hardware processors. The hardware processors acquire moving object information indicating the positions of one or more moving objects including a first moving object to be predicted. The hardware processors generate cumulative map information expressing, on a map, a plurality of positions indicated by the moving object information acquired at a plurality of first time points equal to or earlier than the reference time point. The hardware processors predict a position of the first moving object at a second time point later than the reference time point based on environment map information expressing, on a map, an environment around the first moving object at the reference time point, moving object information acquired at the reference time point, and the cumulative map information.