He did so in a message of greeting to a worldwide congress of exorcists that met near Rome last week.
At the same time, the Pope encouraged the participants to see their work as a "service of liberation and consolation".
They should "accompany the faithful who are actually possessed by evil with prayer and invocation of the powerful presence of Christ, so that God may grant them victory over Satan through the ritual of exorcism."
Special rite of blessing
Around 300 people who regularly take part in exorcism rituals took part in the 15th Congress of the International Association of Exorcists in Sacrofano near Rome; most of them are Catholic priests.
In the Catholic Church, exorcism is a special rite of blessing in which a specially trained pastor attempts to free a person possessed by the devil from evil.
Exorcists need a special authorisation from their bishop for this.
Before an exorcism, they must first check whether the suspected possession of the person concerned is actually a mental illness.
The film "The Exorcist", which was staged with special effects, brought the old ritual back into the public eye in the 1970s.