In these days, there are significant deteriorations in some onshore structures and one of the causes is chloride in concrete.
　There are two origins of choloride; from the materials used and from the sea water as an environmental condition. In'this research, the author compares the influence of these choloride on the corrosion of the embedded steel bars. In addition to this, influenece of the water-cement ratio, the kind of cement and the existence of crack is also investigated.
　The conclusions are as follows:
(1) Several factors are recognized to be influencial on the corrosion of the embedded steel bars. Among them, the environmental condition, the kind of cement and the existence of crack are more influencial than the chloride content of mixing water and the water cement ratio.
(2) The negative influence of chloride in the mixing water relatively decreases with age. Especially, in the case of in sea water and with the existnece of crack, the influence can not be recognized at the age of one year.