Disclosed is an automatic cleaning device for toilet seats. A motor drives upper and lower transmission gear sets. The upper transmission gear set, after reduction, drives a scrub disk, while the lower transmission gear set has a main gear in front to engage a toothed ring at the inner ring of the toilet seat. The turning of the main gear enables the toilet seat to rotate about 360 degrees. Another motor drives a lateral gear set to further drive a drag mechanism. When the two cantilever arms of the drag mechanism swing, the link arms at a lower end will drive a drag block which has two slide blocks.
