A roller-type ratchet device is used for a wrench which includes a driving head defining a receiving hole and a plurality of actuating recesses. The ratchet device includes a driving body secured in the receiving hole to rotate with the driving head, a follower secured between the driving body and the driving head and having a plurality of fixed portions each mounted in a respective one of the actuating recesses, a plurality of locking members each secured in a respective one of the fixed portions of the follower to move therewith, and each pressing the driving body, and a direction control knob pivotally mounted on the driving head and engaged with the follower for moving each of the locking members in the respective actuating recess between different positions.