Energy management system and energy management method

According to one embodiment, an energy management system includes an energy supply device (10) and an energy demand device (200). The energy management system comprises a first device (11), a second device (201), storage sections (21, 211), calculating sections (20, 210). The first device (11) is applied for the energy supply device (10). The second device (201) is applied for the energy demand device (200). The storage sections (21, 211) are included in the first device (11) and the second device (201), respectively, and store a condition as to comply with an adjustment request of energy supplied from the energy supply device (10) to the energy demand device (200). The calculating sections (20, 210) are included in the first device (11) and the second device (201), respectively, and cooperate to execute negotiation function calculating an energy adjustment amount satisfying the condition.