Nonresident investors bought 113.87 billion yen more than they sold last week on the Tokyo, Osaka and Nagoya stock exchanges, against net sales of 37.93 billion yen the previous week, according to industry figures.
The strong rebound in Japanese stock prices in recent weeks has enticed foreign investors to return to the Japanese markets, brokerage officials said.
They also cited as a major factor the tightened controls on short selling -- a step included in the government's recent package of measures to fight deflation.
The tightened restrictions on dealings involving sales of borrowed shares forced investors to buy back shares to cover their short positions.
Some investors, including hedge funds, had profited from falling markets by short selling.
The government is apparently aiming to underpin falling markets that have cut deep into the latent value of stocks held by banking institutions and other companies.
For all of February, nonresidents chalked up 48.5 billion yen worth of net purchases on top of 285.4 billion yen in January.
Among domestic players, trust banks were net buyers for the fourth straight week, reflecting a growing flow of money from public and private pension funds.
Those banks bought 106.2 billion yen more than they sold on top of 103.7 billion yen the previous week.
This brought their total net purchases for February to 275.7 billion yen.
City, long-term credit and regional banks were net sellers for the 22nd consecutive week as their cross-shareholding ties continued to unravel.
Life and casualty insurance companies were net sellers for the ninth week in a row.