A calibrating device for calibration of an image measurement system. The calibrating device includes a main body having an upper surface, and a characteristic portion, which serves as a benchmark for calibration and is in the form of a recess formed in the upper surface of the main body, wherein the characteristic portion includes a side surface extending in a direction crossing the upper surface, and a bottom surface extending in a direction crossing the side surface, the bottom surface has an optical reflectance lower than an optical reflectance of the upper surface in relation to light identical to each other. This can provide a calibrating device for calibration of an image measurement system, which can detect the characteristic portion on the calibrating device stably, precisely and independent of the illumination conditions, which is less costly and can be easily handled.