Since a case of primary aldosteroism was first documented by Conn, J.W. in 1955, several hundred cases have been reported globally while some 200 cases have been known in Japan since the first report was made by Torigai et al. in 1957. In 1965, the first year of the author's experience as a clinician, the author encountered two cases of this syndrome in succession within just 6 months. The author presented the documentation of these cases in pertinent academic meetings and periodicals, which turned out to be the first in Hiroshima at least as documented cases. Aldosterone is the most powerful mineral corticoid produced in glomerular zone of adronal cortex, clinically, primary aldosteronism is characterized by hypokalemia and the continuous hypertension caused by resistance to hypotensive drugs. In this paper, by reviewing existing literature on primary aldosteronism as well as by considering new discoveries on this disease, the author, in the attempt to de open the knowledge and understanding of the pathogenesis of this syndrome, focused mainly on the blood pressure caused by excessive secretion of aldosterone triggered by a very small tumor of 1-2 g in weight developed on adrenal cortex and the fluotuation of mineral in serum. While significant progress has been achieved on the study into the pathogenesis of hypokalemia, the causal mechanism of hypertension largely remains a mystery awaiting further research. It will be the author's utmost pleasure if this paper can play a role of a milestone in such effort.