PURPOSE: To perform measurement of strength in a state further similar to a state in which an object to be measured is used by converting the operation force of a robot, performing a test of the object to be measured for a strength, to operation in two directions extending opposite to each other.

CONSTITUTION: An arm member 42 of a jig 20 for measuring a strength is pressed by a robot for rotation, and a shaft 50 of integral structure is rotated in the direction of an arrow mark D following the rotation of the arm member. In this case, an integrally mounted press arm 54 is also rotated in the direction D, and the arm part of a moving part being an object to be measured is pressed and displaced downward through a shaft 55 and a protrusion 56. The rotation force of the shaft 60 is transmitted to a shaft 60, which is rotated. In this case, the shaft 60 is rotated in the direction of an arrow mark E. In this case, an integrally mounted press arm 64 is also rotated in the direction E, and the arm part of a moving part being the object to be measured is pressed and displaced upward through a shaft 65 and a protrusion 66. Namely, an operation force converting mechanism formed through various kinds of constitution converts an operation force, energized by the robot, to operation in tow directions extending opposite to each other.