To provide a connection device for a side spoiler for a vehicle and the side spoiler capable of reducing the number of work processes for connection and the number of connection parts and connecting the side spoiler with a vehicle body easily in a short time.

This connection device 1 for the side spoiler is used to connect the side spoiler with the vehicle body. A connection part 3 attached to an internal wall of the side spoiler and a nipping part 5 fixed to a lower end of a side sill of the vehicle body are integrally formed at both ends of a main body 2 like a flat plate. This side spoiler is connected with the vehicle body by the connection device 1. A connection projecting part having a flat face opposing to a side face of the connection part 3 provided protrudedly in the vertical direction for the main body 2 like the flat plate is formed on an internal wall face.