In a robot device, an action selecting/control system (100) includes a plurality of elementary action modules each of which outputs an action when selected, an activation level calculation unit (120) to calculate an activation level AL of each elementary action on the basis of information from an internal-state manager (91) and external-stimulus recognition unit (80) and with reference to a data base, and an action selector (130) to select an elementary action whose activation level AL is highest as an action to be implemented. Each action is associated with a predetermined internal state and external stimulus. The activation level calculation unit (120) calculates an activation level AL of each action on the basis of a predicted satisfaction0level variation based on the level of an instinct for an action corresponding to an input internal state and a predicted internal-state variation predictable based on an input external stimulus.