Ketu is to appease the planet Ketu. Ketu Puja is very useful & beneficial puja, since it's worship strengthens benefic Ketu & increases its positive influence and pacifies malefic effects of the planet & neutralizes its negative effect. Ketu Puja is recommended for those having malefic Ketu or wrong placed Ketu as per horoscope.

The planets are to propitiated against their evil influences, to ward off them, the Ketu Puja is done with faith to ward off all evils of Ketu as per the horoscope.