Although Ms Harman will still be in charge of women's issues, she will supported by Joan Ruddock, the member for Lewisham Deptford.
However, it emerged that she will be working for free as she will not draw her ministerial salary. The limit for the number of ministers on the payroll has been reached.
The Department of Social Security already has a special unit for women and its head is to chair a ministerial committee on the issue. She will also see all Cabinet committee papers to assess their impact on women.
Ms Harman's staff have argued that her strong commitment to women's issues would ensure that they remained high on the agenda.
Ms Ruddock was an environment spokeswoman in opposition, but had not been given a government job following the election. Ms Harman said: "Joan has a strong record on women's issues. She will play a key role in our work."
Polly Toynbee, page 23