Home gateway is in always-on state whether traffic flows or not and thus a waste of power is caused in case that any traffic does not flow. This paper proposes HGESM (Home Gateway Energy Saving Mechanism) which reduces energy consumption in home gateway. The proposed HGESM supports energy saving by switching or keeping processor mode according to the type of service (real time or non-real time service). We verify that the proposed HGESM has lower power consumption than the existing scheme.