PURPOSE: To determine the desired inking position on a metered long substance with high precision in a simple manner.

CONSTITUTION: By the use of an inking ruler 1, the positioning levers 3 and 4 are relatively shifted by each equal distance by the action of an end determining shift mechanism only by positioning one end and the other end of a core member 31a by the positioning levers 3 and 4, and the original point scale of a ruler body 20 is automatically positioned on the center line O of the core member 31a. In this state, the position of the desired inking line 35 on the core member 31a can be easily determined by viewing the metering scale of the ruler body 20. Accordingly, the necessity of carrying out the work for obtaining the whole length L and the center line O is obviated, and the numerical value handling work can be reduced drastically. Accordingly, the inking positions on the core member 31a can be carried out with high precision in a simple manner by any operator independently of skillfulness, and the working efficiency can be improved drastically.