This machine automatically measures the stiffness of paper, film, nonwoven textile, etc. By changing the specimen size and selecting a weight on the pendulum, it enables measurements of a wide range of stiffness. One end of the specimen is held on the movable clamp. The other end is set at a position so that it overlaps the top of the pendulum by 6.4mm. Then the arm with the specimen is slowly moved to deflect the specimen as the load increases, thereby tilting the pendulum. At last, specimen detaches from the pendulum. The maximum rotation angle at that detaching moment is captured by a sensor, to calculate and display stiffness. This machine releases the operator from tiresome calculation involving the specimen size and weight and position of the mass, as with the conventional tester, permitting accurate and rapid measurements, thereby increasing productivity in research and develop activities.