To realize weight and cost reductions by forming a compact link device.

A first cam groove 23A having an independent groove 232 and a second cam groove 23B having an independent groove 233 are formed in a driving plate 22, and a common groove 231 is formed in part of the driving plate 22 and is shared by the first cam groove 23A and the second cam groove 23B. In the independent groove 232 of the first cam groove 23A, the groove depth of the independent groove is formed longer than the independent groove 233 of the second cam groove 23B as a stepped groove which has a large-diameter groove and a small-diameter groove. The independent groove 233 of the second cam groove 23B is formed into such a straight shape that does not pass through the driving plate 22. The common groove 231 has the large-diameter groove which comprises the same angle groove depth with the independent groove 233, and a groove width which is almost the same as the outside diameter of the small-diameter part of the independent groove 232. A first driving pin 24A comprises a large-diameter column part and a small-diameter column part and which is formed in a stepped shape. A second driving pin 24B is formed into a straight column part.