A device for withdrawing blood for diagnostic purposes including a lancet and a lancet drive having a loadable elastic drive spring provided within an elongated housing. A relaxing motion of the drive spring is converted into a puncturing motion to move the lancet at high speed in a puncturing direction until its tip exits out of an opening of the housing. The device includes a transmission in the housing that has an input side that transforms the motion of a loading element along a linear loading path into a rotational motion of a lancet drive rotor to load the lancet drive rotor by tensioning the drive spring. When the lancet drive is triggered, the output side of the transmission converts a rotational motion of the lancet drive rotor, driven by the drive spring, into the puncturing motion in a direction along the main axis.