Smart city is rapidly gaining attention, and more than 400 sites are recognized all over the world, as of the year 2012. Smart city is regarded as an urban area where its social/public infrastructure is efficiently managed using the advanced technology such as ICT, environmental science. The original goal was to form a technology basis for low carbon society or efficient community in energy usage, however, the recent concept grows to include resiliency of society and its infrastructure in disastrous situation. This trend is apparent in Japan, especially after the East Japan Great Earthquake in 2011. Smart city is designed as a social infrastructure to share community resources in emergent situations, and to bring efficiency in energy use in a normal situation. This paper introduces typical smart city projects in the world and community services developed under smart city context.