The invention mainly relates to a training device for a board sport involving the use of a board, that is essentially characterized in that it comprises at least a first (2c) and a second (3c) main support line of the board (6) extending from at least one upper attachment point (4, 5; 51, 75, 77, 81, 83) located above and at a distance of the board (6) as far as a first (13) and a second (14) support element of the board (6) respectively, each extending transversally under the board (6) and each comprising a bearing part (15, 16) on which the lower face (15) of said board (6) is supported.The device according to the invention is particularly applicable to surf training, the board then being a surf board.