Nottinghamshire Police said officers were investigating whether any criminal offences had taken place at the care home.
A spokeswoman said: "A police investigation has been launched after concerns were raised about the standard of care provided to residents at Autumn Grange in Sherwood Rise."
Police will be speaking to former residents and their families and will work closely with partner agencies to establish if any criminal offences have taken place."
More top news
Seventy pupils at the Grange School in Runcorn were held in isolation for refusing to remove Marie Curie daffodils from their blazers.
A paedophile hoarding thousands of child sex abuse images has been jailed for three years after leaving his camera's memory card on a bus.
X Factor presenter Dermot O'Leary has annouced his retirement from the popular ITV talent show after eight years.