The purpose of the present invention is to provide a cage farming apparatus capable of easily harvesting adult fish within a cage by simply lifting the cage toward the surface of the sea by a buoyancy means being lifted and lowered toward the surface of the sea and the floor of the sea. The cage farming apparatus comprises: a buoy floating on the surface of the sea； a central structure placed on the floor of the sea and connected to the buoy by a lifting rope； a buoyancy means, which is inserted in the lifting rope so as to be liftable and lowerable and lifts up along the lifting rope by buoyancy because of the injection of a material, such as air, having a specific gravity lower than that of seawater, or lowers down along the lifting rope by weight because of the injection of seawater； an auxiliary structure spaced apart from the central structure at a predetermined distance and positioned on the floor of the sea； a cage positioned on the upper side of the auxiliary structure and connected with the buoyancy means by a connecting rope； and pulleys formed on the central structure and the auxiliary structure, and guiding movement of the connecting rope such that the cage is lifted up toward the surface of the sea or lowered down into the sea according to the lifting or lowering of the buoyancy means.
