MAXI (Monitor of All-sky X-ray Imager) was launched in 2009 and installed on the International Space Station.It consists of the Gas Slit Camera (GSC) and the Solid-State Camera. The GSC, gas proportional counter array, covers the energy range from 2.0kev to 30keV while the SSC, CCD cameras, covers the energy range from 0.7keV to 7keV. In the seminar, I will focus on the SSC. The SSC consists of 32 CCDs in total with a mechanical slit. The CCD performance is gradually degrading in orbit due to its harsh radiation environment. I will report on the diffuse X-ray background maps obtained in energies of 0.7–1.0, 1.0–2.0, and 2.0–4.0 keV, respectively. They are the first ones that were derived with a solid-state instrument. The diffuse soft X-ray background was discovered in the past by using sounding rocket experiments and studied in detail by ROSAT All Sky Survey (RASS). After that, we learnt that the solar wind charge exchange (SWCX) was a nuisance in X-ray astronomy, particularly below 1.0keV. The SWCX is believed to depend on the solar activity and seriously affects the diffuse X-ray background. RASS was done in high solar activity while SSC was done in low solar activity separating about 20 years. Our result shows a good correlation with that by RASS.
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