Speaking in the Scottish Parliament the Deputy First Minister said it would be a red line in any negotiations with the European Union about membership if Scotland votes yes in the referendum.
Ms Sturgeon was asked what line could not be crossed in negotiations about entry requirements.
The question came after comments by the European Commission president Jose Manuel Barroso, in which he said achieving European Union membership as an independent country would be "difficult".
Ms Sturgeon said any suggestion Scotland would not be a member of the EU was counter to the principles of the body.
Glasgow Labour MSP Drew Smith said: "Scotland can only join by negotiation and agreement of the member states. Can I ask the Deputy First Minister what will be Alex Salmond's red line?"
Ms Sturgeon said the case for Scotland being a member was based on "continuity of effect".
She said: "Scotland has been in the EU for 40 years but the suggestion we find ourselves outside simply because of exercising our right to self determination would be an absolute affront to democracy and to the EU."
She was later asked by Maryhill and Springburn Labour MSP, Patricia Ferguson, what the red line would be, and whether it would be on currency, the Euro or VAT rates.
She said: "You have to sign up to the treaties.
"They apply whether the Deputy First Minister likes it or not."
Ms Sturgeon replied: "I have made the position clear. An independent Scotland led by this government would not be in the Euro. It will be a red line, we would not be in the Euro."