Andrej Bajuk was one of the first to get his hands on Slovene euros
The euro symbol was displayed on flags, balloons and t-shirts at New Year's Eve celebrations in the capital Ljubljana as Slovenes prepared for the switch.
The existing currency, the tolar, will be phased out over the next 14 days.
Slovenia is the first of the 10 new EU members that joined in 2004 to have met the economic requirements needed to adopt the single currency.
It becomes the 13th country in the euro zone.
The Slovene minister of finance, Andrej Bajuk, was one of the first people to withdraw the Slovene euros from an electronic cash machine.
Misho seemed more interested in his bottle of beer and kebab than macroeconomic responsibility.
Slovenes unruffled by euro
"We are extremely happy and proud . We took this as a national project and we have indeed achieved and fulfilled all the criteria to make this a reality," he said.
"It's extremely important for us. I am sure that the net benefits that we are going to reap are positive and substantial, that we are going to increase our exports and that things will move faster and better than before."
Inflation concerns
Slovenes seem to be relaxed about the change, says the BBC's Nicholas Walton in Ljubljana.
The euro becomes the fourth currency they have used in less than two decades. The tolar was introduced after Slovenia split from Yugoslavia in 1991.
Even critics of the government are broadly in favour of the change, saying it will encourage the government to reform the economy more quickly.
But some fear it will lead to inflation.
Celebrating New Year in Ljubljana, Nina Peskar, a 20-year-old student, said: "I look forward to the euro because it will make travel abroad easier but at the same time I'm afraid prices might go up."
Location of Slovenia in Europe.

On January 1 2007, Slovenia officially joined the  and adopted the  as its new official currency. At the same time, , which were available as a "starter kit" from December 15, became legal tender everywhere in the Eurozone.

A period of dual circulation, when both the former currency, the  and the euro will be accepted, will only last until January 14. All banks are going to exchange tolars into euros at the official rate of 239.64 SIT per 1 EUR at no commission until March 1, 2007. After that date it will be possible to exchange tolar banknotes (unlimited) and coins (until 2016) only at the Bank of Slovenia.

Most  already dispense euro banknotes with the rest to follow in the following days. Commercial banks automatically converted all tolar accounts into euros and online banking systems will be accessible to their users again on January 3. Even though January 1 and 2 are non-working days in Slovenia, many banks will be opened from 10:00 to 14:00 on both days, available only for one service: exchanging tolars to euros and larger euro banknotes into smaller units.