The Subaru/XMM-Newton Deep Survey (SXDS) is a new deep Optical/X-ray survey which aim to take full advantage of the capabilities of the Subaru Telescope and the XMM-Newton. The SXDS is part of an ambitious project to obtain extensive multi-wavelength data across a ∼ 1.3 deg² region of sky. Other wavelength data (infrared, submillimeter, and radio) are being pursued through various facilities. Combined with suitably deep images at other wavelengths the SXDS would provide an accurate census of the contents of the Universe without suffering from the biasing effects of large-scale structures. This paper describes the location, size and depth of this survey.