TOKYO, Nov 20 (Reuters) - Goldman Sachs' Japan president Masanori Mochida has decided to retire at the end of the year after more than 38 years at the investment bank, according to an internal memo seen by Reuters.

The internal memo dated Sunday from Goldman CEO David Solomon said Mochida will become a senior director, without mentioning who would succeed his role as president.

Mochida, 68, joined Goldman Sachs in 1985 as an associate in the corporate finance department from Japan's Dai-ichi Kangyo Bank, one of the three predecessor banks of Mizuho Bank . He became co-branch manager of Goldman Sachs Japan in 1999.

Mochida, also a member of Goldman's management committee, is credited with significantly expanding the U.S. investment bank in Japan, handling many major deals including the government's releases of Nippon Telegraph and Telephone shares.

"Masa has served as an invaluable advisor to our most important clients across Japan and beyond on countless transactions, helping them advance their strategic objectives with Goldman Sachs at their side," the memo said.

The Financial Times, which first reported his departure last week, said Mochida was on track to retire from the bank at some point in 2024.

However, it said that over the past few days the decision had been made to speed up that process amid growing internal concern that the bank needs fresh leadership in Tokyo as competition for deals with rival U.S. investment banks intensifies.

(Reporting by Makiko Yamazaki; Editing by Stephen Coates)