To provide an accessory control device for a vehicle capable of improving fuel economy by reducing a load on an internal combustion engine as an accessory based on information on a traveling environment of the vehicle in future.

An accessory control device for a vehicle 1 includes: a navigation system 5 for obtaining information on the traveling environment of the vehicle 1 in future; an engine ECU 4 for determining the idle state of the vehicle 1; and an air conditioner ECU 6 for controlling an accessory load which is applied on an engine 2 of a compressor 10 connected to the engine 2 of the vehicle 1. When the idle-off state is determined by the engine ECU 4 while the idle-on state of the vehicle 1 in future is predicted based on the information on the traveling environment, the air conditioner ECU 6 reduces the accessory load.