PURPOSE: To prevent errors accompanying an interlocking fulcrum by utilizing a double lever to set the moving direction of the interlocking fulcrum between a drive side lever and driven side lever parallel to the displacement adding direction given to the point of force of the drive side lever.

CONSTITUTION: A predetermined contracted displacement is given to the force point 7 of a drive side lever 5 by advance to a drive lever 8. As a result, the drive side lever 5 is pivotally displaced about the center of a fulcrum lever 3, and a transmitting lever 16 moves parallel to the displacement adding direction of the drive lever 8 to transmit to the driven side lever 10 the displacement contracted one step through the lever 16. Also, the driven side lever 10 subjected to the displacement is displaced pivotally about the center of a fulcrum lever 3 in the reverse direction so that displacement contracted by two steps is taken out of a driven lever 20. By this contraction of the double lever is obtained the displacement less than submicron.