"The figure given by the coalition... is about 22,000 dead since the start of operations in Iraq and Syria," Jean-Yves Le Drian told the France24 news channel, adding that the figure was "approximate".
He also sounded upbeat about a series of military successes against IS in recent months.
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"We haven't seen a large offensive by Daesh for some time," Le Drian said, using an alternative name for the group. "Daesh is in a very fragile position but we must remain very careful," he added.
The coalition air strikes against IS began in the summer of 2014 and intensified following last November's jihadist attacks in Paris, with strikes notably targeting IS oil production facilities, a key source of income for the group.
In a major setback for the group, IS lost the Iraqi city of Ramadi to US-backed local forces last month.