The ticket was purchased on Friday, but store owners Patsy and Tony Reddan have no idea who the lucky winner may be.
Their daughter, Kate, said: "We have had no indication who the winner might be and we might never know. They mightn't have checked their ticket yet or they could just decide to remain anonymous. This is our biggest win yet and there’s great excitement around the place."
The Reddan's previous record was set when a Euromillions player won €430,000 on a ticket bought from their store.
"We’ve also had a few smaller wins like €10,000 on scratchcards but this is the first time we’ve had an actual Lotto jackpot winner," Kate said.
Mayor of Clare and Sixmilebridge John Crowe said: "It was very funny after Mass with everyone looking at each other and asking if they won it."
The winning Irish Lotto numbers drawn on Saturday, July 5, 2014, were 10, 18, 23, 26, 42, and 45. The bonus number was 13.
"Whoever won it, everyone here is delighted for them and we wish them the best of luck," Crowe said.
The next Irish Lotto Drawing is on Wednesday, July 9, 2014. The estimated jackpot is €2 million.