Just more than half of Scots questioned, 51%, said they "feel a loyalty to Great Britain" compared with 28% who "don't feel any loyalty".
Nineteen per cent said their loyalty "has risen in the past year".
The survey, for mobile phone provider 02, showed Scots were less loyal to Great Britain than the English and Welsh but more loyal than people in Northern Ireland.
A spokesman for the pro-UK Better Together campaign said: "The separatists would have you believe that we are all desperate to break up Britain, to ditch our shared history and to cut ties with a country that we are an integral part of. We all know that this is utter nonsense."
A spokesman for the pro-independence Yes Scotland campaign said: "People can still feel British while wanting an independent Scotland.
"Becoming independent will allow us to choose a different economic and social path while keeping the links of culture, family and history."