PURPOSE: To detect the displacement of the contactor and to perform movement control over the contactor on the basis of the displacement and angle of rotation by fitting the contactor onto a shaft, rotating the shaft by a specific angle on a specific plane parallel to the shaft with a command, and bringing the contactor into contact with a model.

CONSTITUTION: A processor 1 when actuated reads an approach command out of an RAM3 to read area data which is not work condition data out of a data memory 4 and stores it in a working memory 5. Then, the sign of speed data is inverted and inputted to a D/A converter 6 as an Z-axial feed speed VZ. When a Z-axial motor 12Z rotates and a pulse is generated, the current position is updated. The processor 1 reads the current Z-axial position and monitors whether the motor reaches a specific deceleration position or not. Consequently, a tracer head moves down toward the model at a low speed and when it contacts the model, a digital value obtained by an A/D converter 9 is read by the processor 1. A probe is set almost perpendicularly to a measurement surface and measurement precision is improved.