An information processing system includes a controller that controls the supply route of electric power in a house, a determining unit that determines, based on the driving schedule of an electric vehicle, necessary energy with which the car battery of the electric vehicle should be charged, and a detector that detects first charge energy with which the car battery is charged. The controller selects, based on the necessary energy and the first charge energy, which one of electric power supplied from a power company and electric power supplied from the car battery is to be consumed in the house.