A merge support system includes a first detection unit and a second detection unit for detecting a position and a speed of an approaching vehicle in a traffic on a main lane and a position and a speed of a subject vehicle, an information provision unit for providing information for a driver of the subject vehicle and a control unit for calculating a merge speed of the subject vehicle relative to the traffic on the main lane and a merge position relative to the traffic on the main lane. The control unit calculates the merge speed and the merge position on the main lane based on the position and the speed of the approaching vehicle and the subject vehicle, and the control unit controls the information provision unit for providing a calculation result of the merge speed and the merge position for the driver of the subject vehicle.