The invention relates to an ink oscillating device for an offset machine, comprising an ink oscillating rod, an ink oscillating rod rotating shaft, an ink oscillating gear, two bearing pedestals and two bearings. The ink oscillating device for the offset machine is characterized by further comprising an end-face cylindrical cam, a fastening mechanism, two cam rollers and two roller connecting shafts. The end-face cylindrical cam is provided with a round sliding through hole in the axis direction; the ink oscillating rod rotating shaft is arranged in the round sliding through hole; the cylindrical surface of the end-face cylindrical cam is connected with the inner side wall of the ink oscillating rod through a fastening mechanism; the two cam rollers are arranged on the ink oscillating rod rotating shaft through the two roller connecting shafts and are located at the two ends of the end-face cylindrical cam; and the two cam rollers are in contact match with the corresponding end surfaces. The ink oscillating device for the offset machine has a simpler and compacter structure; the ink oscillating gear cannot slide on the shaft to wear, so that the transmission precision and the service life of the ink oscillating gear cannot be affected, and the ink oscillating gear has longer service life; and the ink oscillating amount of the ink oscillating rod can be adjusted conveniently by adjusting the installation position of the cam rollers on the roller connecting shafts.