At least 34 people are injured, according to the authorities in the South American country.
The accident occurred on Saturday in the region of Ancash, north of the capital Lima.
According to rescue personnel, the bus overturned and fell 100 meters into the ravine.
The police living in the area worked all night towards Sunday to be able to free the survivors and the victims' remains from the bus.
The cause of the fatal accident is still unknown, but fatal traffic accidents are not uncommon in Peru due in part to poorly maintained roads.
In February this year, 20 people lost their lives after a bus crashed into a ravine near the northern city of Tayabamba.