The president took his daughters, Sasha and Malia, to One More Page Books in Arlington, Virginia, on Saturday afternoon.
The White House says Obama was promoting an effort called "small business Saturday" to encourage shoppers to patronize mom-and-pop businesses after the Thanksgiving holiday.
At the store, Obama held up his BlackBerry, apparently looking up a book title as he spoke with shop owner Eileen McGervey. He said "preparation" was the key to his shopping.
Obama brushed off a reporter's question about the looming "fiscal cliff," saying "we're doing Christmas shopping."
The White House says Obama bought 15 children's books that will be given as Christmas gifts to family members.