A lane change estimation device includes a detection unit that detects a surrounding situation of an own-vehicle, a first index value deriving unit that derives a first index value according to a traveling-direction-related relationship between each of a plurality of pairs of vehicles, each pair including two vehicles among the own-vehicle, a first vehicle traveling in front of the own-vehicle in a first lane in which the own-vehicle travels, a second vehicle traveling in front of the own-vehicle in a second lane adjacent to the first lane, and a third vehicle traveling behind the second vehicle in the second lane on the basis of the surrounding situation of the own-vehicle, and an estimation unit that estimates a probability of lane change of the third vehicle on the basis of the first index value derived and a lateral position of the third vehicle.