Although the boundary layer that is formed between the rapidly rotating inner accretion disk and the white dwarf surface has been known as a hard-X-ray emitter, its geometry and structure has not been well understood yet. We aim to investigate the boundary layer structure with SS Cyg, the brightest dwarf nova, by means of a soft X-ray component with the BI CCD, a fluorescent Fe K-alpha line with the FI CCDs, and a continuum reflection by the white dwarf surface with the HXD PIN. It is of great use to observe states of a different mass accretion rate, and hence we propose to observe both in quiescence and in outburst.