The report said Apple and Softbank have agreed to co-develop the phone for sale as early as this year. The device is expected to carry both the Softbank and Apple brands, the report said, without citing the source of the information.
Softbank, which said last month it would buy Vodafone's Japanese mobile phone business, appears to be looking to use the power of Apple's brand to compete against mobile market leaders NTT DoCoMo and KDDI Corp.
Last August, Apple and handset maker Motorola introduced a music-playing cellphone known as the Rokr that has received disappointing reviews for its design and the limited number of songs that can be stored on the device.
Speculation has mounted that Apple is developing its own mobile phone -- popularly labeled the iPhone -- that will combine the stylish design of its iPod music and video player with mobile phone features.
Pundits from blog rumor sites to Wall Street analysts have speculated on the meaning of a string of patent applications filed by Apple Computer that stretch back several years and could indicate its ambition to build its own mobile phones.
Also fueling speculation about Apple's next potential moves is a newly disclosed Apple patent application for a display screen that detects multiple, simultaneous touches or "near touches" to produce separate signals to a device.
Touch-screen technology is widely used in so-called smartphones that have a variety of functions such as phones, e-mail, contact lists, Internet access and cameras.
Apple's technology would allow users to perform several touch-activated tasks at once, unlike other devices that process only one screen-activated function at a time, according to the application with the U.S. Patent and Trademark Office, which was filed on May 6, 2004 and published on Thursday.