Provided is a collision avoidance support device capable of terminating traveling direction automatic control at a timing appropriate for a driver. A traveling direction automatic control unit is configured to: terminate the traveling direction automatic control when a predetermined control termination condition is satisfied at a time before an operation start time at which a vehicle starts changing a traveling direction by the traveling direction automatic control; continue the traveling direction automatic control until an appropriate driving operation enabled time at which a predetermined required reaction time passes since a time at which an alert unit starts issuing an alert, when the predetermined control termination condition is satisfied at a time after the operation start time and before the appropriate driving operation enabled time; and terminate the traveling direction automatic control when the predetermined control termination condition is satisfied after the appropriate driving operation enabled time.