The present invention provides a robot apparatus that can perform appropriate actions in accordance with the ambient conditions, and a method of controlling the behavior of the robot apparatus. The robot apparatus includes a data-acquiring unit that acquires data, externally and/or internally, a subject-identifying unit that identifies a subject performing an action, by using the data externally acquired, a condition-recognizing unit that recognizes external conditions and/or internal conditions, by using the data externally acquired and/or the data internally acquired, an action-pattern acquiring unit that acquires an action pattern of the subject, by using the data externally acquired, a storage unit that stores action data representing the action of the subject, in association with condition data and subject identification data, the condition data representing conditions external and/or internal of the robot apparatus, and the subject identification data identifying the subject, and an action-performing unit that performs actions, wherein the action-performing unit performs an action represented by the action data stored in the storage unit, in accordance with the identification data and the external and/or internal condition data, when the subject-identifying unit identifies the subject.