Santen Pharmaceutical Co., Ltd. (参天製薬株式会社, Santen Seiyaku Kabushiki-gaisha), is a Japanese pharmaceutical company, specializing in ophthalmology.

With its ophthalmic products Santen holds the top share within the Japanese market and is one of the leading ophthalmic companies worldwide, with its products being sold in over 50 countries.

[4] In 2014 Santen announced that it has entered into an agreement with Merck & Co. to purchase Merck's ophthalmology products.

[5] Santen has 3 plants located in Hōdatsushimizu, Ishikawa, in Tampere and in Suzhou, 21 subsidiary companies located in Japan, the US, the Netherlands, Finland, United Kingdom & Ireland, Spain, Switzerland, Italy, France,[6] Germany, Sweden, China, South Korea, Taiwan, India, Thailand, Malaysia, the Philippines and Singapore.

Its R&D center is located in Ikoma, Nara.