A device that will enable the decoration on a music box to sway front and back while it moves up and down, particularly to a type of device that will enable the decoration on a music box to sway to front and back while it moves up and down. It is mainly composed of a base on which is a first motor that will turn the spring plates of the music wheel to produce music, a gear set that is driven by a second motor, a propping post piercing a ball collar and a ring cover and a top cover; when the second motor drives the gear set and the driving wheel to rotate, the propping post will move up and down in the through hole of the ball collar, and the ball collar will sway to front and back inside the ring collar, so that the movement of the wooden horse will be more realistic.