  In cooperation, the workers must know how co-workers behave. However, an
agent's policy, which is embedded in a statistical machine learning model, is
hard to understand, and requires much time and knowledge to comprehend.
Therefore, it is difficult for people to predict the behavior of machine
learning robots, which makes Human Robot Cooperation challenging. In this
paper, we propose Instruction-based Behavior Explanation (IBE), a method to
explain an autonomous agent's future behavior. In IBE, an agent can
autonomously acquire the expressions to explain its own behavior by reusing the
instructions given by a human expert to accelerate the learning of the agent's
policy. IBE also enables a developmental agent, whose policy may change during
the cooperation, to explain its own behavior with sufficient time granularity.
