Family members say Cyril Smith, who has dementia, was lucky to escape with his life after the incident at the Parkside home on 5th May.
His son Jeff Smith of Rushpole Close, Forest Town said: “We received a phone call from the manager of the home saying ‘your dad is in King’s Mill Hospital, he’s been seriously hurt’.
“We went to the hospital and found him in a terrible state.
“He was black and blue.
“His face was a mess - his ear was swollen like a balloon and his hands arms and body were covered in bruises.”
It is thought Mr Smith wandered into the room of another resident when the incident took place following a confrontation.
Jeff Smith is questioning how the incident was allowed to occur and why the police were not informed until nine days later.
He told Chad “I am appalled that something so serious can happen to a vulnerable old man like my dad at a care home that is supposed to be looking after him.”
An Ambulance took the injured pensioner to King’s Mill Hospital A and E.
Mr Smith said: “Social Services were contacted by A and E who were shocked by the state dad was in.”
The family met with Social services and Age UK on 14th May.
He said: “They told us the home should have contacted them and the police should have been informed straight away.”
Mr Smith has now been moved to a different care home.
“Parkside even sent us a bill for £22 for the taxi which took my dad to the hospital for a follow up treatment on his ear, said Mr Smith.
A spokesman for Nottinghamshire Police said: “We are currently investigating an alleged assault on an 86-year-old man at the Parkside Home in Mansfield on 5 May.
“At this time our enquiries are continuing.”
The Chad contacted Parkside, located in Olive Grove, Forest Town, who refused to comment.