During systematic search for high thermoelectric force in the iron base alloys, the author's group found a new alloy which have the Heusler structure. It consists of Fe, V and Al with the atomic ratio of 2:1:1. When V loses, the p-type conductor with high Seebeck coefficient was formed. When V was added to excess 25 mol%, it becomes n-type conducter with negatively large Seebeck coefficient. The current topics in this new alloy was reviewed.