An adjustment device of an auxiliary carry device connected to a baby stroller includes an expanding unit and a folding unit. The folding unit is connected to a board. The expanding unit has two cables, two links and a base. The two cables are connected to the baby stroller, and the two links are connected between the cables and the base connected to the board. The expanding unit makes the two links simultaneously be pivoted away from or toward each other. The folding unit is connected between the board and the expanding unit to pivot the base. The board is pivoted relative to the baby stroller to save space, and the cables provide cushion feature to the board.