The High Court in Glasgow heard that 62-year-old James Ainsworth told two of his female victims: "I'm a police officer, no-one will believe you."
In court Ainsworth pleaded guilty to seven charges of sexually abuse and one of rape. The offences were committed between 1965 and 1990 in Ayrshire and Dumfriesshire.
Advocate depute Kath Harper, prosecuting, said that Ainsworth's predatory sexual behaviour began when he was just 14.
The court heard that Ainsworth sexually abused one of the girls in the police house in Ayrshire where he was stationed.
Ainsworth was placed on the sex offenders' register and will be sentenced next month.
Judge Norman Ritchie QC remanded him in custody.
Defence QC Andrew Lamb will give his plea in mitigation then.