Triggered by the Fukushima Daiichi Accident, new regulatory requirements came into effect in 2013. Mitsubishi Heavy Industries, Ltd. (MHI) has been working on measures to improve the safety of nuclear power plants so far in order to contribute to the restoration of public confidence in nuclear power. This report presents examples of support service for electric power companies and safety improvement for restarting nuclear power plants, which are activities we have been working on, as well as our support for installation of specialized safety facility for further safety improvement. By performing these activities continually, we will keep on working with electric power companies to improve the safety of nuclear power plants.