The present invention relates to a novel method for preparing thienopyrimidine compound having an activity of selectively inhibiting tyrosine kinase, specifically the mutant epidermal growth factor receptor tyrosine kinase and a novel intermediate used therein. According to the method of the present invention, the industrial mass-production of the compound of Formula 1, which is useful as a therapeutic agent for non-small cell lung cancer induced by the mutant epidermal growth factor receptor tyrosine kinase, can be implemented more conveniently and efficiently than the conventional technology.
