1. A behavior control apparatus to control behavior of a device capable of sensing a state of an environment and selecting an action on the basis of a sensing result, the behavior control apparatus comprising: predicting means for learning the action and change in the state of the environment and predicting change in the state of the environment caused by a predetermined action on the basis of the learning; planning means for planning a behavior sequence to achieve a goal state from a present state on the basis of the prediction made by the predicting means; and control means for controlling each action of the behavior sequence planned by the planning means and learning an input/output relationship if the goal state is achieved through the action, wherein the planning means adds predetermined one or more perturbations to the action output from the control means to generate samples and uses the samples as action options for search, and the planning means changes a dispersion value of a probability distribution of the perturbations based on progress in learning by the control means.