PURPOSE: To three-dimensionally measure an object to be measured at a low cost with intermediate to low accuracy by making an operator to softly bring the front end of a contact into contact with an arbitrary point on the object to be measured by operating a handle and input the shape, dimension, and contact angle of the front end section of the contact to a personal computer.

CONSTITUTION: A revolving frame 12 is horizontally and rotatably fitted to a swivel base 13 through a swing bearing and an encoder 14 is fitted to the axial center of the frame 12 so as to detect the rotation angle between the base 13 and frame 12. The operator of the title measuring instrument softly brings the front end section of a contact 3 with an arbitrary measurement point on an object 2 to be measured by moving a handle 5 and instructs a personal computer 1 to fetch measurement data. The computer 1 inputs parameters, such as the shape, dimension, contact angle, etc., of the front end section of the contact 3 and calculates the rotational angles of the frame 12 and arms 10 and 11 detected by encoders 14, 15, and 16. Then the computer 1 is made to display or record the relative three-dimensional position between the front end section of the contact 3 and the arbitrary point on the object 2.