A contra-rotating propeller system is installed between a rudder horn of a ship and shaft support at an engine-output side. The system includes a propeller shaft rotatably supported by the rudder horn and the shaft support, respectively, a front propeller fixed to the propeller shaft, a counter rotating gear set installed on the rudder horn and connected with the propeller shaft, and a rear propeller connected to the counter rotating gear set and disposed between the rudder horn and the front propeller.