To provide a motorized mechanical pencil, in which a certain quantity of lead 3 is delivered by advancing a lead holding means, which allows the advancement of the lead 3 and checks its retreat, by shrinking an energizingly driving type shape memory alloy 9 through the turning ON of an automatic switch caused by the retreat of a lead guide 2 due to the use of the lead 3 by writing.

In the motorized mechanical pencil, the automatic switch, which turns ON by the retreat of the lead guide 2 and OFF by the advancement of the lead guide 2, is comprised and further the lead holding means, which allows the advancement of the lead 3 and checks its retreat, is comprised by providing balls 13 at the head part 12A of a chuck 12 so as to thrusting these balls 13 against the tapered surface 11B of a fastener 11. The lead holding means is advanced through the shrinkage of the energizingly driving type shape memory alloy 9 caused by the turning ON of the automatic switch.