Support device

A detection unit detects one of a plurality of inter-vehicle areas as an area candidate where the own vehicle can perform lane change. A calculation unit calculates a required inter-vehicle distance which should be secured between the own vehicle and a nearby vehicle upon lane change to the area candidate. An extraction unit extracts, within preset allowable ranges, a standby time and a target speed used for estimating an estimated inter-vehicle distance as lane change conditions which are conditions for the estimated inter-vehicle distance to be equal to or more than the required inter-vehicle distance. When the lane change conditions are extracted, and a determining unit determines that lane change is possible, a setting unit sets the area candidate as the lane change area.