PURPOSE: To eliminate the positional restriction of a motion pivot point at the middle point of a link by forming an elliptic orbit so that a cross point is taken as a reference point, an interval between a pivot shaft and a support shaft is taken as an elliptic radius along a vertical straight line, and an interval between the support shaft and a connecting shaft is taken as an elliptic radius along a horizontal line.

CONSTITUTION: A link 2 is installed extendedly in upper slant direction toward the sliding direction of a slider 1, and a connecting shaft 5 with a vertical motion body 8 is formed at the top of it. Also an intermediate motion support shaft 4 slid along an elliptic orbit 6 is provided on a straight line connecting a pivot shaft 3 to a connecting shaft 5 at the middle part of the link 2. Then the elliptic orbit 6 is so formed that a cross point O of a horizontal line L extending to the extended motion line of the pivot shaft 3 and a vertical line L2 crossed with the horizontal line from the connecting shaft 5 is taken as a reference point, an interval (a) between the pivot shaft 3 and the support shaft 4 is taken as an elliptic radius along the vertical line L2, and an interval (b) between the support shaft 4 and the connecting shaft 5 is taken as an elliptic radius along the horizontal line L1. Thus the positional restriction of a motion pivot point at the middle point of the link 2 is eliminated so as to widen the freedom degree of equipment design.