PURPOSE: To simplify the structure by providing a coordinate measuring system with a temperature correction unit and measuring the length thereof thereby determining a temperature correction coefficient.

CONSTITUTION: A temperature correction unit 24 is disposed within the measuring range of a three-dimensional measuring system 10 with the columnar body and tubular body of the unit 24 being positioned substantially in parallel with the axes of the coordinates of the system 10. A control section 36 is prestored with reference lengths of the columnar body and tubular body at a reference temperature and coefficient of thermal expansion of the tubular body. The control section 36 calculates a temperature correction coefficient at the time of measurement based on prestored data and the lengths of the columnar body and the tubular body measured by a probe while furthermore performs temperature correction of the system 10 and a work. This constitution realizes simplification of the structure while reducing the cost.