Abstract: A sign serving as a deterrent to unauthorized parking is mounted on a post which is resiliently supported by a base in a normal vertical position and is adapted to be deflected into an inclined position by the car bumper when overriding the base in driving head-in into the parking space. The base has a vertical wall which guides the post in returning from the inclined to the normal vertical position preventing rearward deflection and has an open front shaped to permit the forward deflection of the post through a predetermined horizontal angle. An axial helical tension spring for a tubular post or a spring biased pivot for a channel shaped post connects the respective post to the base for the resilient deflectability.A wire slide-guard is mounted along the post spaced from the sign to engage the car bumper and any protruding portions of the undercarriage for smooth passage therealong to facilitate the deflection and prevent the sign from locking thereon when the car backs out of the parking space.