To facilitate the inserting and removal of a pin, eliminate the backlash at the time of connection and stably attach a tractor to a working machine in an apparatus for connecting a top link bracket attached to the rear of the tractor to a support bracket on the side of the working machine by inserting or removing the pin.

This apparatus for connecting a working machine of a tractor is obtained by boring the first circular intermediate hole 4 on the side of a top link bracket 1 and the second square intermediate hole 4a on the side of a support bracket 3 in close vicinity to a pin hole 2 of a pin 8, inserting and passing a locking pin having an eccentric cam surface so as to pass through the first intermediate hole 4 and the second intermediate hole 4a, rotating the locking pin with the shaft center as the center and thereby removing the backlash of the pin hole 2 at the time of connecting the top link bracket 1 to the support bracket 3.