PURPOSE: To surely discharge a residual lead by providing a residual lead discharge means which vibrates a pencil to forcibly drop the residual lead upon completion of a lead supply action by which the residual lead held only by a pencil lead displacing tube of the push button-type pencil is pushed out by a new lead.

CONSTITUTION: In a plotting head 2 which relatively moves in X-Y directions in an automatic drafting machine, a raising/lowering driver 10 is fixed on a base 8, and a pen holder 22 detachably holding a push button-type pencil 20 is provided on a raising/lowering body 14. The pencil 20 is provided with a lead chuck mechanism which is brought to holding/releasing states by the vertical movement of a pushing mechanism 34a. A pencil lead holding position is changed by vertically moving a lead displacing tube 38 relatively to the mechanism. In this invention, upon completion of a lead supply action by which a residual lead held only by the pencil lead displacing tube 38 is pushed out by a new lead, the displacing tube 38 is abutted on a lower butt plate 30, and the pencil 20 is subjected to a redidual lead discharge vibration processing in which the pencil 20 is finely vibrated in an axial direction, for example, at an amplitude of 1mm to forcibly drop the residual lead.