

- April 1957
- The founder Sutejiro Ohara has established "Koka Pharmaceutical Company" as the precursor of the company
- November 1964
- The company was made into a corporate, and "Ohara Pharmaceutical Co., Ltd." was established. (Capital: 3 million yen)
- August 2001
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Strategic capital alliance signed with Itochu Chemical Frontier Corporation, Inabata & Co., Ltd. And CBC Co., Ltd. (Capital: 160,250,000 yen)
- May 2006
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Capital reinforcement with Itochu Chemical Frontier Corporation, Inabata & Co., Ltd., CBC Co., Ltd., Pharma Plan Co., Ltd., SBIC West Japan and Shiga Bank (Capital 481,750,000 yen )
- February 2007
- Obtained all stocks for Sankyo Yell Pharmaceutical Co., Ltd. From Sankyo Kabushikigaisha, jointly with the group companies
- June 2008
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Transferred head office functions to Shiga Research Park
Introduction of resources from Toho Pharmaceutical Co., Ltd. And Yell Pharmaceutical Co., Ltd. (Capital: 681,950,000 yen)
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Tokyo Head Office
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R&D Center
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Kami Factory