In a letter to supporters, campaign manager David Plouffe said the Obama campaign raised the funds with an average donation of $68 (€42).
The Obama campaign and the Democratic National Committee have a combined total of $72m (€45m) in the bank.
John McCain's campaign announced last week that the Republican had raised $22m (€35m) in June, his best month ever.
Senator McCain and the Republican National Committee have $95m combined on hand for the general election.
Last month, Senator Obama caused a storm after going back on an earlier undertaking to accept public financing for his campaign, giving him an advantage, as he will be able to raise as much money as he wants to buy vital television ads.
Mr McCain has already said that he will accept public financing for his campaign, which caps his spending between the Republican convention in early September and the general election, at $85m.
