Three quarters (75 per cent) of the survey respondents held an investment product - ranging from direct stock holdings to KiwiSaver, managed funds and bonds - up from 72 per cent last year.
FMA chief executive Rob Everett said the lift in overall confidence was encouraging.
"The fact those earning between $50,000 and $100,000 per year are a lot more confident points to broader participation in sharemarkets and financial markets more generally. This reinforces the increasing importance of KiwiSaver, as people watch their balances grow," he said.
But only 53 per cent of survey respondents said investment materials were helpful for making informed decisions about whether to invest or not.
"While it's disappointing that half of investors didn't find investment materials useful, this is consistent with other feedback we've received," said Everett.
Under the new Financial Markets Conduct Act, which came into force last month, investment materials are required to become simpler and easier for retail investors to read and understand.
Investor materials in this context include the new product disclosure statements, which will replace the current prospectuses and investment statements, the FMA said.