PURPOSE: To control the measurement pressure and to achieve accurate marking- off by providing a switching device for operating either a control device for executing measurement at a specific measurement pressure or for operating a fine-adjustment device for executing marking-off operation.

CONSTITUTION: The interval measuring instrument has a post 1 with a leg part 2, and the post 1 made of a hollow body is connected to a rail 4 that functions as the guide of a slider 14. The slider 14 includes a slider part that is formed as an adjustment mechanism 5 and a slider part that functions as a measurement part 6. The edge of the measurement member 6 is formed as spherical calipers 12, and the measurement member 6 has a shaft 11 that can be fixed by screws 10. A fine-adjustment device 39 enables the measurement member 6 to move slightly for the adjustment mechanism 5. In this case, a screw 48 functions as a switching device and operates either a control device 19 for executing measurement at a specific measurement pressure or a fine- adjustment device 39 for executing marking-off operation. In the case of the marking-off, the calipers 12 are changed to a marking-off needle.