To provide a connecting device where relative rattling between a rotating body and a shaft is removed and speed irregularity in rotating them is effectively prevented, and an image forming apparatus equipped with the same.

In the connecting device for connecting the shaft 36 and the rotating body 30 comprising a helical gear connected to the shaft 36 and rotating together with the shaft 36, a recessed part 38 is formed on the shaft 36 and also a projecting part 39 is formed on the inner peripheral face of a mounting hole formed on the rotating body 30. By fitting the recessed part 38 and the projecting part 39, the shaft 36 and the rotating body 30 are brought into press-contact with each other.