Foreign investors bought a likely record amount of Japanese shares last week, brokerage data showed on Thursday, as buyers took heart from the central bank's surprising easing measure and the pension fund's decision to increase its allocation for domestic stocks.

Foreigners bought a total of 2.23 trillion yen ($19.26 billion) worth of Japanese shares, including both futures and cash stocks, during Nov. 4-7, according to data provided by the Japan Exchange Group, which operates the Tokyo Stock Exchange and the Osaka Exchange.

It was a four-day trading week with Japan's national holiday on Monday.

The total amount was seen as a record, according to Mitsubishi UFJ Morgan Stanley Securities and Nomura Securities which track historical data.

Foreign investors bought Japanese futures worth 1.4572 trillion yen and cash stocks worth 769.1 billion yen.

Futures data includes Nikkei futures, Nikkei mini futures, Topix futures and Topix mini futures.

On the other hand, trust banks, which manage corporate pension trusts and national pension fund trusts, were net sellers of Japanese shares during the week.

They sold 402.4 billion yen worth of Japanese futures and cash stocks, the biggest amount since the fourth week of May 2013, when Ben Bernanke, the then U.S. Federal Reserve chairman, shocked the market by saying the Fed may start tapering its asset purchases.

"The huge amount suggests that pension funds like the GPIF were one of the big sellers," said Norihiro Fujito, a senior investment strategist at Mitsubishi UFJ Morgan Stanley Securities. "Topix's valuation has risen, so it makes sense that the GPIF wants to take profits when valuation gets high."

The price-earnings ratio of the Topix rose above 17 times estimated profits on Nov. 4 from 14.7 times in October, Fujito said.