1. An interface device having at least one unit to be operated, the device that is used to select one of a plurality of contents items to be processed, the device comprising: demand estimating means of obtaining situation data for grasping a situation of a user and estimating a demand of the user based on the situation data; group recommendation order setting means for setting a group recommendation order of a plurality of contents groups obtained by classifying the contents items in accordance with a demand estimated by the demand estimating means; assigning means for associating a predetermined contents group with the unit to be operated in accordance with the group recommendation order set by the group recommendation order setting means, wherein the predetermined contents group is high in the group recommendation order set by the group recommendation order setting means; and process object selecting means for selecting, as an object to be processed, one of contents items belonging to the predetermined contents group associated with the unit to be operated in response to an operation on the unit to be operated.