Idemitsu Kosan Co.,Ltd. (出光興産株式会社, Idemitsu Kōsan Kabushiki-gaisha) is a Japanese petroleum company. It owns and operates oil platforms, refineries and produces and sells petroleum, oils and petrochemical products.Idemitsu is the second largest petroleum refiner in Japan, after Nippon Oil. It was ranked as the 262nd largest company in the world by revenue in Fortune Global 500 (2008). It is number 26 in petroleum refining.