Lignac is a commune in the Indre department in central France.

Lignac is located in the southwest corner of the department. It borders the ancient regions of Berry, Poitou, and La Marche in the foothills of the Massif Central. The village lies within the parc naturel régional de la Brenne, a region noted for its lakes and wildlife. The river Anglin forms part of the commune's eastern border.