In a televised statement, French President Francois Hollande said the law, which would mandate all government ministers to publish details of their financial assets, would be proposed "in the coming weeks."
The announcement came a day after former Budget Minister Jerome Cahuzac admitted he had a secret bank account.
He resigned two weeks ago after an investigation was begun into the allegations. Cahuzac said in a blog post he set up the account 20 years ago.
"Jerome Cahuzac lied," Hollande said in his statement, which was recorded and broadcast after he left for a state visit to Morocco.
He said the minister wouldn't receive any special protection from the government.
Under Hollande's proposal, Parliament members convicted of fraud and corruption would be banned for life from holding public office. The legal system also would be reformed, the president said, to restore confidence in magistrates.
Marine Le Pen, leader of the Front National, termed the potential legislation "petty measures."
She called on the government to resign, saying, "beyond this Cahuzac affair, the list [of scandals] is too long."