The invention relates to a transmission device for a punch press. The transmission device comprises a power transmission shaft, a first crankshaft and a second crankshaft, wherein the power transmission shaft is provided with a first gear; the first crankshaft is provided with a second gear; the second crankshaft is provided with a third gear; the transmission device further comprises a fourth gear meshed with the first gear; the fourth gear is arranged on a central shaft; the central shaft is parallel to the first crankshaft; the central shaft is also provided with a fifth gear which is meshed with the second gear; an idle gear is arranged between the fourth gear and the third gear, and is arranged on an idle gear shaft; the idle gear shaft is parallel to the first crankshaft; and the idle gear is meshed with the fourth gear and the third gear in a way of synchronous transmission. According to the transmission device, the diameters of the second gear and the third gear are greatly reduced on the premise that the strength is guaranteed, the power is transmitted by the idle gear arranged between the second gear and the third gear, and a pressure center of the punch press is really guaranteed and enlarged, so that the cost and the difficulty of gear manufacture can be reduced.