Lane change assistance device and lane change assistance method

Disclosed herein is a lane change assistance device, including: a change time setting unit configured to set a change time required for the lane change; a yaw angle acquisition unit configured to acquire a yaw angle of an own vehicle before starting the lane change; and a steering control unit configured to control a steering unit of the own vehicle to perform the lane change in the change time set by the change time setting unit, wherein when the yaw angle acquired by the yaw angle acquisition unit is a yaw angle in a state where the own vehicle approaches a target lane designated during the lane change, the change time setting unit sets the change time shorter than in other states, and when the yaw angle acquired by the yaw angle acquisition unit is a yaw angle in a state where the own vehicle stays away from the target lane, the change time setting unit sets the change time longer than in the other states.