Japan was the first Asian nation in the nineteenth century which successfully implemented modernization. Therefore, to ensure its economic progress it sought new markets to sell its products. Iran, also with various motivations, to compensate for its backwardness sought to develop its relations with Japan. The present study attempts to study the ups and downs of trade relations between Iran and Japan in the contemporary era. Based on its findings, the study reveals that the First World War and the Bolshevik revolution in Russia boosted the trade between Iran and Japan and Japan became one of the Iran's top ten trade partners and the Japanese products officially entered Iran. Due to official relations, the trade activities between the two nations entered a new phase. Iran needed to be industrialized. Therefore, it hired Japanese experts and specialists to accelerate its progress. The trade balance between the two nations was equal in the beginning years of the Reza Shah era but gradually the Japanese benefitted more and this process continued.