As many as 800 jobs could go including sales team employees Hiromitsu Iwasaki, the unit's president, told reporters. The reductions come as Pfizer has six drugs that are being reviewed in Japan.
Pfizer's research and development plant in Japan also faces closure along with manufacturing facilities in the US and France. However, Mr Iwasaki could not comment on whether this planned closure was still to go ahead.
When Pfizer previously reported axing 10,000 jobs worldwide, it said that from 2003 to 2008, it will have reduced its network of manufacturing plants from 93 to 48.