An insider told Bloomberg that 100 new staff have already been taken on, with a further 400 potentially set to follow between now and the end of 2011.
Morgan Stanley is attempting to build a successful private bank, offering loans, investment advice and savings products to its wealthiest clients.
The bank's wealth management unit recorded interest income of $191 million for the first quarter of the year, far below the $1.1 billion figure made at Bank of America Merrill Lynch.
In May, Hisaki Endo, a representative director at Morgan Stanley Capital Group Japan, said that the firm is looking to double the size of its Japanese commodities business over the course of the next two years.
"The commodities sector is lagging behind Europe and America, given the economy's size," he told Bloomberg.
By Asim Shah