1) Table salt (=NaCl=common salt=salt) is scientifically characterized, and the significant role in dietary and daily life has generally been discussed from the standpoint of human ecology. 2) In dietary life, salt fundamentally gives a deliciousness to dishes and nutro-physiologically functions to keep homeostasis in the body. Meanwhile, the excessive intake of salt often causes the high blood pressure and induces several fatal diseases. 3) In daily life, salt derivatives(Na-, Cl-compound) are quite useful widely over food, clothing and housing. Meanwhile, some of them especially organochlorine compounds often pollute the environment and damage the humans and or ecology as so-called environmental hormone resulting in dioxins. 4) For the ambivalence of salt in health and environment, humans, but not salt, are wholly responsible. The fact would go not only to salt but also generally to resources on the earth. 5) Humans should adequately be moderate in utilizations and consumptions of salt and or resources. Everything must be kept with in bounds. This conception would surely bring the stable maintenance and the sound development to the system of human ecology as well as global ecology.