The resignation of Munir, who played a key role in the movement to restore judges deposed by former military ruler Pervez Musharraf, was expected as media reports had said he was likely to quit because his mother is unwell.
He sent his resignation to President Mamnoon Hussain, saying he could not continue performing the duties of Attorney General because of personal reasons.
In an unrelated development, National Database and Registration Authority (NADRA) chairman Tariq Malik sent his resignation to the government, citing the larger interest of the organisation.
In December, the government had sacked Malik from his post. He approached the Islamabad High Court, which suspended the notification on his sacking on December 3.
The case is still pending in court.