The demonstration project on energy networks of electricity, heat, and hydrogen in an existing apartment building has been initiated to evaluate authors' proposal. The authors proposed the setting up of an energy system by fuel cells and energy networks of electricity, hot water, and hydrogen in residential areas. In such networks, some homes are equipped with fuel cell stacks, fuel processors, hydrogen storage devices, and large storage tanks for hot water. The energy network enables the flexible operation of the fuel cell stacks and fuel processors. A demonstration has been started since April 2007. The demonstration is presented in a small apartment building, which was constructed for experimental purpose in Osaka City. Two homes on the 3rd floor and four homes on the 4th floor, total six homes are involved to the demonstration. The six families are spending their completely normal daily life using the system. Three small PEM fuel cells have been installed, and the electricity and hot water from the fuel cells are shared via an internal electricity grid and a hot water pipe. Hydrogen production facility, a small storage and a hydrogen pipe have been installed as an infrastructure to supply hydrogen to the fuel cells. The energy flow process from hydrogen production to consumption in the homes is demonstrated. The operation results including the performance of each system component such as fuel cell and lessons learned are reported.