To provide a connecting device which can signally connect and mechanically easily connect plural components in a limited space.

In a connecting device 100 to signally connect and mechanically mutually connect plural components, and in a first connecting piece 110 which has a signal connecting terminal and is set in a first component C1, a second connecting piece 120 which has a signal connecting terminal and is set in a second component C2 and a third connecting piece 130 which has a signal connecting terminal to connect the signal connecting terminal of the first connecting piece 110 or the signal connecting terminal of the second connecting piece 120 and is set in a third component C3, this third connecting piece 130 has connecting fixing parts 200 and 210 which connect/fix the first connecting piece 110 by moving it in the first direction H running almost along a connecting surface of the third connecting piece 130 and connect/fix the second connecting piece 120 by moving it in the second direction V crossing the first direction of the third connecting piece 130.