Labor will pledge a financial boost for more than 160,000 women in a new policy that aims to narrow the gap between women's and men's superannuation savings for retirement.

Opposition Leader Bill Shorten will outline the $400 million plan on Wednesday with a vow to make economic security for women one of his priorities at the next federal election.

The Labor scheme would deliver a top-up payment for thousands of super accounts every year for those on parental leave, addressing one of the factors that leaves women with about 60 per cent of the retirement savings of men.

Labor leader Bill Shorten surrounded by female members of his frontbench on Tuesday. Credit:Alex Ellinghausen

Mr Shorten told Fairfax Media the measure to improve economic security "should be an election priority" because of the gap in the average super balances between men and women at their retirement.