To selectively telescopically extend or retract a plurality of writing units from the end of a barrel by so providing two types of the units as to cooperate with a slide top at the front side of the top, longitudinally moving the top by the rotation of a rotary shaft upon rotation of a rear barrel, and extending or retracting the end of the unit from the end hole of the front barrel.

The double writing instrument comprises an intermediate barrel 30 provided at between a front barrel 39 and a rear barrel 43, and a rotary shaft 33 rotatably disposed in the rear inner hole in a range of substantially 180 degrees with respect to the barrel 30 to be fixed to the barrel 43 and formed with a protrusion at the front side. A pair of slide tops 45a, 45b formed at the inside opposed with oblique cam grooves 47a, 47b engaged with the protrusion 35 are so guided as to make it possible to merely move longitudinally in the inner hole of the barrel 30, and writing units 1a, 1b are so provided as to be cooperated with the front slide top of the tops 45a, 45b. The tops 45a, 45b are alternately moved back and forth by the rotation of the shaft 33 upon rotation of the barrel 43, and the ends of the units can be extended or retracted from the end port of the front barrel.