The Boeing 737 jet sustained €200,000 worth of damages after rolling more than 40 metres from its runway parking spot and hitting the fire station hanger on Wednesday afternoon, La Repubblica reported.
As well as shredding part of the tail, the accident, which happened shortly after the jet had landed and passengers disembarked, also ripped off the front of the hanger, the newspaper said.
Ryanair said in a statement on Thursday that it "has asked the ground handling agent (Groundcare) to investigate why it failed to properly secure a Ryanair aircraft at Rome Ciampino Airport."
Groundcare staff at Ciampino airport were on strike at the time of the accident.
The company explained that the "parked and unoccupied aircraft rolled back and made contact with a remote building damaging its rear stabiliser."
The jet is currently being replaced and will shortly return to service, the company added.