BERLIN — Germany’s Parliament on Friday approved a quota system that will require leading companies in Europe’s biggest economy to have at least 30 percent women on their supervisory boards starting next year.

The quota will apply to the directors of more than 100 listed companies, though not to their management boards. Another 3,500 firms will be required to set targets of their choosing to raise the number of female directors and women in other leadership positions.

“If there are no equal opportunities at the top of companies, there are none in other areas either,” Manuela Schwesig, the minister for women and families, told ZDF television.

Lawmakers from Chancellor Angela Merkel’s governing coalition of conservatives and Social Democrats backed the legislation Friday. Opposition lawmakers who argued that it didn’t go far enough abstained.

“A real quota for women must apply to all companies,” said Caren Lay, a lawmaker with the opposition Left Party.