Among the previously unpublicised cases was a planned attack, foiled in May, on an air force training school in the southern town of Salon-de-Provence, the minister said, without giving details.
Another plot targeting "a barracks, a police station or a supermarket with hostage-taking," was averted in January.
"The threat remains strong," Collomb told a parliamentary committee considering government proposals for new anti-terror laws.
"We see that we are moving from an outside threat to an internal threat, and we have to be able to adapt to the evolution of this threat," he added.
The parliamentary deputies are considering the controversial terrorist law plans which are designed to replace, on November 1, the state of emergency which France has been under since Islamic State jihadists struck in Paris in November 2015, killing 130 people.
The new laws -- a campaign pledge of President Emmanuel Macron -- will give authorities the power to place people under house arrest, order house searches and ban public gatherings without the prior approval of a judge.