Otsuka Holdings (TYO: 4578), abbreviated OPC, is a pharmaceutical company headquartered in Tokyo, Osaka and Naruto, Japan. The company was established August 10, 1964. As of 2012, OPC employed 40,000 people worldwide. The company focuses on pharmaceuticals related to nutrition. The company is also known for the popular sports drink Pocari Sweat and the best-selling energy drink Oronamin C. Otsuka Pharmaceutical also developed Abilify (aripiprazole), an approved drug treatment for schizophrenia and bipolar disorder, which they claim has a better side effect profile compared with other antipsychotic drugs. As of 2013, annual sales of Abilify were over $8 billion a year, making it the highest grossing drug worldwide.

OPC joined the Tokyo Stock Exchange through an initial public offering (IPO) on December 15, 2010, at which time OPC was Japan's No.2 drug maker by sales after industry leader Takeda Pharmaceutical Company. The IPO debuted at $2.4 billion, making it the largest for a pharmaceutical company up to that time.

In early 2012, Otsuka announced it would focus its "future operations on CNS disorders and oncology". This decision necessitated a revision in the terms of an agreement with UCB to end collaboration on immunology products while continuing collaboration in the CNS area.

In September 2013, Otsuka Holdings announced it had agreed to acquire Astex Pharmaceuticals for close to $900 million.