The present invention enables accuracy inspection and measurement error calibration of a contact three-dimensional measuring machine and an optical three-dimensional measuring machine to be performed by a single inspection master. This inspection master is provided with: measurement holes with which contactors of a contact three-dimensional measuring machine can contact; and optical indicators for scattering measurement light from an optical measuring machine, wherein the distance between two or more measurement holes and the distance between two or more optical indicators are defined as having a specific distance relation. The distance between two optical indicators of the inspection master is measured by the optical measuring machine, the distance between two measurement holes is measured by the contact three-dimensional measuring machine having measurement traceability, both actually measured distances are compared with each other, and the measurement traceability of the optical measuring machine is confirmed. Detection accuracy of optical indicators is enhanced by providing non-scattering parts around the optical indicators.
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