A hand tool having a reciprocally driving mechanism includes a driver, a body and a blade assembly. The driver has a driving shaft and a trigger. The driving shaft is controlled by the trigger and has a gear portion. The body has a driving gear having a teeth portion disposed on a top of the driving gear for engaging the gear portion. The driving gear has a stub eccentrically disposed on a bottom of the driving gear for driving a driving unit to move and to relatively drive a driven rod. The driven rod is connected with the blade assembly. The driving shaft is able to drive the blade assembly to reciprocally move for providing a higher torsion, a higher driving force, and a higher cutting speed, such that the hand tool is suitable for cutting a thicker workpiece.