The index jumped five points during the three months to March to a high of net 18%. Those confidence levels had not been seen since the end of 2010.
ASB head of wealth advisory Jonathan Beale said rising confidence in public shares had contributed to the optimistic mood from investors.
''Kiwi investors have, over the past few years, regarded the sharemarket with an air of caution in comparison to some other investment classes such as investment property and term deposits.''
However, it appeared that public awareness surrounding recent Government state-owned enterprises share offers had put the share market back on the radar of investors in the March quarter, he said.
The percentage of respondents believing term deposits and managed investments would yield the best returns was down two points each in the quarter. Expectations that public shares would have the highest returns jumped more than three points to 10%.
Investor confidence in Canterbury had increased 10 points to a net 20%, the highest it had been in the region since 2008. It was also the first time since 2011 that confidence had been higher in Canterbury than the rest of the country.
KiwiSaver retained its ''solid popularity'' with local investors, sitting at 14%.
Mr Beale said New Zealanders would remain confident in the scheme as good returns continued and balances grew with the minimum contribution rising to 3%.
Craigs Investment Partners broker Greg Easton said the New Zealand sharemarket was a laggard last week after some exceptionally strong performance in recent weeks.
However, a little more than halfway through the June quarter, the NZX remained up 4% and on an annual basis, 13.1%.
All of the action last week occurred in offshore markets, he said. The Standard and Poor's 500 rose 2.1% for the week and the FTSE, in the United Kingdom, was up 1.5%.
The Dow Jones Industrial Average and the S&P both hit record highs, rising for the fourth week in a row. In each of the last four weeks, both indices had increased by at least 1%, something that US shares had not achieved since late 2011, Mr Easton said.
''The US market is now up an incredible 16.9% year-to-date.''
All S&P sectors were up. Financials and industrials had risen the most. With the S&P now at 1667 points, year-end targets for all of the Wall Street banks had been surpassed, he saidLater this week, investors will gain more insight into what the world's top central bankers are thinking.
There is a Bank of Japan rate decision, minutes from the Bank of England and the US Federal Reserve's policy committee, and Fed chairman Ben Bernanke will be giving testimony to Congress and a slew of manufacturing data is due from Europe.
