The woman found the alligator after leaving the restaurant, picked it up, put it in a bag and took it to the police station in Pierrelatte in the Drôme, where the gendarmes locked it in a sobering-up cell, which usually houses drunks.
The animal, which is only about a metre long, is a Chinese alligator, a protected species whose jaws are never strong enough to attack humans, and is worth several thousand euros.
On Wednesday it was taken back to the crocodile farm from which it escaped two months ago.
It is now being kept in a reinforced enclosure along with four other Chinese alligators.
But another alligator, which escaped as the same time as the one which has been found, is still out there.
Crocodile farm boss, Samuel Martin, fears that it will not survive the winter cold, although that may not be the principal concern of local people.