A board-to-board connection structure includes a first circuit board, a second circuit board, and a connector. The first circuit board includes a first base layer and a first outer circuit layer. The second circuit board includes a second base layer and a second outer circuit layer. The connector electrically couples the first circuit board and the second circuit board. The connector includes a housing, a first electrical connection portion, and a second electrical connection portion. A side surface of the first circuit board includes a first conductive layer electrically coupled to the first outer circuit layer. The connector is coupled to the first conductive layer through the first electrical connection portion. The second circuit board is located in the housing, and the second electrical connection portion is electrically coupled to the second outer circuit layer.