The present disclosure provides an energy management system capable of improving energy efficiency. The energy management system includes: a fuel cell configured to supply energy used in a facility; a first hydrogen supply unit configured to supply hydrogen to the fuel cell by causing a power generation apparatus that uses renewable energy to perform water electrolysis; a second hydrogen supply unit configured to supply hydrogen to the fuel cell by reforming natural gas supplied via a pipeline; and a control unit configured to determine a ratio between hydrogen supplied from the first hydrogen supply unit to the fuel cell and hydrogen supplied from the second hydrogen supply unit to the fuel cell. The control unit determines the ratio in accordance with a percentage of heat energy and energy other than the heat energy with respect to the energy used in the facility.