The law obliges the government to come up with a policy for offering women more opportunities in recruitment and promotion, state-run NHK news agency reported.
It also called for creating an environment where women can balance work and family.
The law requires the central and local governments and large companies to set numerical targets for female recruits and managers. Employers are required to make the figures public.
The law also calls on smaller firms to draw up similar plans.
According to the Japan Institute for Labour Policy and Training, the percentage of women in management positions in 2013 stood at around 11 percent, while the percentage in the US, Britain, France and Sweden was between 30 percent and 40 percent.