An automatic yarn end finding device for a spinning bobbin comprising a conveyor belt for transporting a spinning bobbin fitted on a peg tray, a gate-shaped suction tube which is located intermediate the passage of a spinning bobbin and which can be passed by a spinning bobbin, a rotary cutter located at one of a pair of base portions of the suction tube for releasing and cutting a tail portion of spinning yarn on a spinning bobbin, a stopper also located at the one base portion of the suction tube for stopping a spinning bobbin which has come to a position opposing to the rotary cutter, and a rotational driving device for driving a spinning bobbin stopped by the stopper to rotate.