A fluttering prevention apparatus for a lever of a pumping device includes: a lever bracket including a first side coupled with a lever, a center portion formed with a hollow hole, and a second side formed with insertion holes; a clutch cam including a first side provided with protruding portions inserted into the insertion holes of the lever bracket; a clutch drum having a first side formed with a seat groove to receive the clutch cam is seated therein; and a spindle coupled to the hollow hole of the lever bracket through center portions of the clutch drum, the clutch cam, and the housing, thereby inhibiting the lever bracket from fluttering with respect to the clutch drum.