Monitor of All-sky X-ray Image (MAXI) started operation as an X-ray all-sky monitor on the Japanese Experiment Module ‘Kibo’ Exposed Facility of the International Space Station in August, 2009. MAXI continuously monitors the X-ray variability once every about 90 minutes for 1000 X-ray sources covering the entire sky on time scales from a day to a few months over a broad energy band (0.5 – 30 keV). We report the overview of MAXI mission and scientific highlights of MAXI in its first 1 year.