PURPOSE: To provide a marking device wherein marking work can be performed one-handed, a mark can be set on a part covered with scale and which is convenient for handling, in a device for setting a marking line and a mark hole on the surface of an object to be measured.

CONSTITUTION: A measuring tape 2 in which a thin steel made scale 1 having a retaining tool 8 at its tip end is wound and housed in a case 3 so that it can be pulled out from a pulling port 4 is equipped, and a marking-off pin 13 provided with a through hole 16 permitting passing of the scale 1 is fixed on the side face 12 of the scale pulling port of the case 3. The upper edge 17 of the hole 16 is set on the scale face, the pointed end 11 of the marking-off pin 13 is positioned just under the upper edge 17 of the hole 16, and the upper end of the marking-off pin 13 is projected from the upper face of the case 3. A steel material having flat angular sectional area whose width is wider than that of the scale 1 and whose length is longer than that of the side face 12 of the pulling port, is used, the upper edge 17 of the hole 16 is positioned on the front 15 thereof, the lower part of the steel material is narrowed down from the lower position and the pointed end 11 is formed.