Provided is a measuring device which, with respect to a measuring instrument for measuring the length of a cutting tool, measures the distance from a reference position of a machine tool to a tool detection position of the measuring instrument. The measuring device comprises: a movement control unit for controlling movement of a standard tool attached to the machine tool; a detection unit for detecting a detection signal indicating a tool detection position output by pressing-down of the measuring instrument; and an identification unit for identifying the tool detection position of the measuring instrument, on the basis of the position of the tip of the standard tool at the timing of detecting the detection signal. The detection unit detects the detection signal indicating that the tip of the standard tool is present within a tool detectable range including the tool detection position. The movement control unit moves the standard tool in a direction away from the measuring instrument to change the state in which the detection signal is detectable by the detection unit to a state in which the detection signal is not detectable by the detection unit, and then moves the standard tool toward the measuring instrument to change the state to a state in which the detection signal is detectable again by the detection unit. The identification unit identifies the tool detection position, on the basis of the position of the standard tool at the timing of detecting the detection signal again.

A method, an apparatus and a processing center for autonomously measuring a tool or a complete tool, include a tool holder and a tool clamped in the tool holder. The autonomous measurement involves a type of the tool first being autonomously determined, a point on the tool that distinguishes the tool then being autonomously determined according to the type of the tool, functional geometries of the tool being autonomously measured starting from this point, and subsequently a cumulative geometry being autonomously ascertained for the tool from the measured functional geometries.