An adjusting device for a table saw includes a pivot rod adapted to be longitudinally mounted under a tabletop of the table saw, a panel extending downward from the tabletop, a rotatable seat pivotally mounted on the pivot rod, a pivotal seat pivotally mounted on the rotatable seat, and a set of adjusting elements respectively mounted on the rotatable seat and the pivotal seat for adjusting a height and an angle of a saw blade of the table saw. The set of adjusting elements includes a threaded rod provided to precisely adjust the height of a saw blade and a gear provided to precisely adjust the angle of the saw blade of the table saw.