The Council of Trade Unions says official figures show many people have to work longer hours than ever to make ends meet.
Labour Day marks the anniversary of New Zealand adopting an eight-hour working day.
This year coincides with industrial action by teachers, hospital laboratory personnel and others.
CTU secretary Peter Conway says there are nearly 260,000 people without jobs, while more than 100,000 others want more work so they can pay the bills.
Mr Conway says the 2006 Census showed 416,641 people work more than 50 hours per week and the struggle to make ends meet is reflected in the current industrial unrest.