This paper aims at measuring the economic impact of Roppongi Art Night 2015 by input-output tables. Roppongi Art Night is a one-night, all-night extravaganza at Roppongi area and the biggest White Nights Festival in Japan. That conducted 87 programs, such as contemporary arts, preforming arts, media arts, film, and artist talk. Local governments, first class museums (The National Art Center, Tokyo, Suntory Museum of Art and Mori Art Museum), commercial complexes and local shopping streets plan and operate this event. This paper focuses on tourist expenditure and the economic effect is estimated to amount to 21.2 billion yen for Tokyo Metropolitan Government. Moreover, the amount per day (10.6 billion yen) is much bigger than those of another famous art projects. In conclusion, Roppongi Art Night 2015 generates not only artistic and cultural values, but also considerable economic ripple effects. This result shows that Roppongi Art Night will raise Tokyo brand for the 2020 Olympics and Paralympics.