To provide an insert nut which can be installed in a target member easily by screwing, has sufficient resistance against screw fastening and unfastening and is easily manufactured.

The insert nut is formed tubular in which an inner screw part is formed along the inner circumference and an embedded screw part is formed on the outer circumferential surface. The insert nut is characterized in that a plurality of unfastening preventive claws having elasticity are formed in an embedded-side distal end part. It is preferable that each unfastening preventive claw comprises a claw supporting part protruding from the distal end part of the insert nut body and a wing part which extends from the claw supporting part and of which the distal end is formed at an acute angle, on the opposite side of an insert nut screwing direction.