WA continues to have the worst pay gap in Australia, with men paid 25 per cent more than women.
Figures released yesterday by the Australian Bureau of Statistics show full-time female workers get paid an average $452 a week less than men.
Average male full-time earnings in WA average $1788, compared with $1336 for women.
The pay gap has narrowed slightly in WA - down from 26.3 per cent a year earlier - which UnionsWA attributes to the heat coming out of the male-dominated mining sector.
The Workplace Gender Equality Agency attributes the long-standing wage gap to a range of reasons, including discrimination and the undervaluation of occupations dominated by women.
UnionsWA secretary Meredith Hammat said the wage gap not only had a negative effect on female workers now, but would continue to affect them in the future.
"By itself, this is wrong and unfair," she said.
"It also has broader, long-term consequences.
"This means women are financially insecure.
"It becomes even worse when women have children and the pay gap persists for the rest of their lives into retirement through less superannuation."
The WA pay gap is down from its peak at height of the resources boom, when local men earned an average 28.2 per cent more money than women.
But it is now higher than its narrowest differential in 2010 when WA men earned only 23 per cent more than women.
The national pay gap is much lower at 18.3 per cent.
But the national pay gap has increased compared with a year previously when it was 17.5 per cent.
Ms Hammat said this was most likely because of a general reduction in rates and hours for those in insecure employment in the Eastern States.
The other resources-rich State, Queensland, has the second highest pay differential at 23.2 per cent.
This was followed by NSW and SA (16.6 per cent) Victoria (13.9 per cent) and Tasmania (11.7 per cent).
The national pay gap was only 15.9 per cent in 1994 but has hovered at current levels since.
Research by the Workplace Gender Equality Agency shows an increase in women's pay would benefit the Australian economy. It claims that if the gender pay gap was reduced by just one percentage point, Australia's gross domestic product would grow 0.5 per cent.