This paper presents an automatic animation generation method for 3DCG humanoid avatars. We can create 3DCG animation even at the level of individuals by using commercially available software tools. Creating 3DCG animation, however, demands a variety of expertise and a mastery of 3DCG authoring tools. Therefore, people may easily be bothered for creating 3DCG animation contents. To solve the problem, we designed and developed a system allowing even novices to create 3DCG animation contents without special knowledge and programming skills. The proposed method uses Inverse Kinematics (IK) and Interactive Evolutionary Computation (IEC) for readily designing and generating avatar motions. The system only requires users to indicate some evaluation values and creates their preferable avatar motions based on the specified values. Additionally, we propose a new operation method to reduce the users' burden in an IEC-based 3DCG contents generation.