In an email to staff, Jobs wrote, "At my request, the board of directors has granted me a medical leave of absence so I can focus on my health," and added, "I love Apple so much and hope to be back as soon as I can."
In his absence, COO Tim Cook would take responsibility for day-to-day operations once again, but he will continue to stay as CEO and be involved in major strategic decisions.
Apple broke the news on a US holiday but didn't specify the duration of leave. The announcement has raised serious concerns about Jobs health. Jobs, a survivor of pancreatic cancer has been instrumental in Apple's success after he rescued the computer maker in 1996 by returning from a 12-year absence. He is a co-founder of Apple Inc.
Cook who was named COO in 2005 is widely seen as the heir apparent to Steve Jobs. He manages sales, service and support and leads the company's Mac computer division, where sales have been surging over the past few years.
The announcement has caused the company's shares to take a beating of more than 8 per cent. Lately, Apple shares had reached unprecedented heights after announcing the availability of its iPhone to customers of Verizon Wireless, the largest US mobile operator.
Apple is due to report its quarterly results on Jan 18.