To provide a simple-structured furniture overturning prevention device capable of being easily attached to/detached from the existing furniture and securely setting the timing of operation without damaging the furniture or a building or without impairing the outside appearance.

The furniture overturning prevention device is characterized by a bracing function part comprising a bracing part with a bracing means which shoots out from near the furniture and bracing the furniture when there is a risk of overturning of the furniture because of an earthquake, etc., a rear face holding function part, and a tightening function part for connecting the bracing function part and the rear face holding function part in such a way that the gap between the parts can be adjusted and holding and tightening the furniture with the bracing function part and the rear face holding function part. In addition, the bracing part of the furniture overturning preventive device is characterized by the bracing means, a storage part in which the bracing means can be stored, a shooting power part for energizing the bracing means so that the bracing means can shoot out from the storage part, and a stopper part for stopping the bracing means normally at the storage part against the power of the shooting power part, and releasing the stopping when the bottom of the furniture is separated from a floor.