Caernarfonshire (Welsh: Sir Gaernarfon), sometimes also spelt as Caernarvonshire and Carnarvonshire in English, is one of the thirteen historic counties and a former administrative county of Wales.
The county of Caernarfonshire was abolished under the Local Government Act 1972, becoming part of the new county of Gwynedd. The administrative entity of Caernarfonshire was very briefly revived in 1996, when the unitary area of Caernarfonshire and Merionethshire was created. It was, however, renamed Gwynedd almost immediately.