Since the launch of Gefitinib in 2002, various molecular targeted therapies have been developed in the lung cancer area. Due to those effectiveness, the development has been actively pursued even in very rare areas in the lung cancer. The purpose of this study is to determine the treatment status of the use of molecular targeted drugs in lung cancer based on Claims Data in Japan. We used data from patients(316,750) with a definitive diagnosis of lung cancer from Medical Data Vision data, mainly at DPC(Diagnosis Procedure Combination) hospitals from April 2008 to June 2019. The number of prescriptions and the prescription ratio of each drug of EGFR, ALK and BRAF were investigated by year using ATC code and receipt code of prescription record. The prescription ratio by gene mutation was 2013 (EGFR 92%, ALK 8%, BRAF 0%(before launch )), 2016 (89%, 10%, 0.02%) and 2019 (85%, 13%, 1.1%). Five types of EGFR gene mutation therapeutics have been approved and are classified into first to third generations. Until 2017, the first-generation prescription rate exceeded 50%. In 2018, Osimertinib was added as a first-line treatment for lung cancer. As a result, the number of third generations rapidly increased, and first-generation 27%, second-generation 14%, and third-generation 58% from January to June in 2019. In prescription ratios by gene mutation, EGFR, which have a large number of patients in Japan, exceeded 80% in each year. In EGFR, the first generation accounted for more than 50% of the prescriptions from 2008 to 2017, then since 2018 the third generation has been rapidly used, accounting for 58% in 2019. Further, we will investigate the patient characteristics, single agent use, combined use with other agents, and use of switching to other agents.