Abstract
Following the 3rd report, the relationship between the relative position of the three phases “L,S,P” on the peritectic line and the features appearing on the ‾LS≤‾SP peritectic structure was examined. As the result, it has been ascertained that the form of the process of the peritectic reaction shows the peculiarity to the peritectic structure and the appearance of the structure varies with the change of ‾LS⁄‾SP value under some fixed rule.