The service is only available to Mac users in the US
Apple has sold more than a million songs since the launch of its online music service a week ago.
The figure is much higher than record industry executives had predicted, who had expected Apple to reach the million milestone in a month.
"In less than one week we've broken every record and become the largest online music company in the world," said Apple boss Steve Jobs.
The success of Apple's music venture contrasts with other industry-backed, subscription-based music services which have been slow to take off.
Easy to use
Apple's iTunes Music Store is widely seen as one of the most consumer friendly methods of buying music online.
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Copy protection is kept to a minimum. People can keep the songs indefinitely, play them on up to three Macs and on an unlimited
number of Apple iPod music players.
Customers can also can burn unlimited copies of the songs onto CDs.
"Apple has created the first complete solution for the digital music age," said Mr Jobs.
In contrast to other legal music services, there is no subscription fee. Instead songs cost 99 cents (62 pence) per download.
Apple said more than half of the songs were purchased as albums, countering fears that selling music on a per-track basis would undermine album sales.
And more than half of the 200,000 songs offered by Apple were purchased at least once.
Forrester Research analyst Josh Bernoff said Apple's service marked "the beginning of a torrent of innovation" as others moved away from current subscription-based models.
He said that services like Apple's would attract people who currently use file-sharing programs as they would be "unwilling to put up with the questionable software installs and audio quality of free services".
"Our internal measure of success was having the iTunes Music Store sell one million songs in the first month. To do this in one week is an over-the-top success," said Doug Morris, Chief Executive Officer of record label Universal.
Apple is planning to add a further 3,200 tracks to the 200,000 already available, including new albums such as Andrea Bocelli's Tosca and Fleetwood Mac's Say You Will.
The online music service is currently only available in the US for Mac computer users. A Windows version is due by the end of the year.
To cap a good week for the computer maker, the company said it had also received 110,000 orders for its new iPods.
It also reported more than a million downloads of the iTunes 4 music software.