It is difficult to measure the accuracies of the holes with a large length to diameter ratio, e.g. a shaft of a jet engine, cylinder for plastic injection moulding, cylinder liner of an engine for a large ship, cannon, etc. Further, each type of accuracy is measured with a different measuring device. For example, diameter, roundness and straightness are measured by the cylinder gage, roundness tester and autocollimator, respectively. In this research, a probe with a 110-mm diameter is fabricated to measure the accuracies of extremely deep holes. Hole accuracy is measured by scanning the hole wall spirally . A laser interferometer is used to detect the hole shape by measuring the movement of the feeler perpendicular to the hole wall. When the measuring unit is exchanged with a counter-boring head, the probe can be used as a laser-guided deep-hole boring tool . Using this measuring system, the straightness and roundness of holes are examined. The results show that the accuracies show a good correlation with those measured by a measuring device in the market or reliable measuring method.