PURPOSE: To easily supplement a lead or ink by providing means for separating a writing instrument judged to have no lead or no ink by detecting means from a pen carriage, and means for stocking the separated instrument.

CONSTITUTION: A body of a pencil 15 is held by a body 26 and a pawl 27 to hold the pencil 15. Then, when a lead of the pencil 15 is consumed and its state is detected by a detector, a pen carriage 6 carries the pencil 15 to a position of a stocking unit 13 and inserts it to a connecting piece 13b. When upper and lower sides of a flange 16 of the pencil 15 are pressed to converged pieces 18a, 18b of the piece 13b, the pencil 15 is so introduced into inside of the unit 13 as to be disposed along tapered surfaces of the pieces 18a, 18b, and separated from the carriage 6. Then, when the carriage 6 is moved to a central side of a drafting bed 2, the pencil 15 is completely separated from the carriage 6 and retained at the unit 13.