To provide an automatic detachable coupling device capable of automatically coupling drive shafts together and accurately transmitting torque, as well as achieving short time increase and decrease of rotation speed with a small capacity motor and automatic centering.

The coupling is comprised of a coupling shaft 6 which has a tip coupled to a driving clutch 31, a holder 7 which rotatably supports the coupling shaft 6, and an energizing spring 27 which pushes the holder 7 forward, a supporting spring 22 which supports the holder 7 so that the holder can be freely displaced vertically and horizontally, and a free expansion universal joint 5 which connects the coupling shaft 6 to a driving motor 2. A driven clutch 41 is comprised of multiple rotating bodies whose axes are rotatably fixed on an outer surface of a clutch drum and guide holes. The driving clutch 31 is fixed on the outer surface of the clutch drum and comprised of a centering pawl projecting forward and a guide bar projecting forward.