The effect of the commission and the omission on inter-generational ethics is discussed focusing on engineering ethics, environmental problems and Japanese culture. First, the problem of the omission in science field was pointed out and the relation between the omission and the concept of the science and the engineering as one of the academic activities was commented. Although the omission has been overemphasized in the discussion on the environments so as to recover old environment, there is some possibility of bringing unexpected damage on future generation. If the science had stopped developing in the beginning of 20^<th> century, many people could not enjoyed their long lives, comfortable daily lives and interests.