Provided is a connection mechanism which connects a switch portion 20 of a generator 1 to an assembling terminal 11 of a junction box 10 having plural female terminals 12 connected to a generator circuit 13 via a relay connector 30, wherein the relay connector 30 forms a defining wall 31 inside a cylindrical body so that a fitting portion 32 is provided at one side of the defining wall 31 so as to be fitted to the switch portion 20, and plural relay terminals are attached to the other side so as to be connected to the plural female terminals 12, and wherein holes 35 are provided in the defining wall so as to respectively face the front ends of the relay terminals 33. Accordingly, the switch portion 20 and the assembling terminal 11 are integrally and directly connected to each other via the relay connector 30.