An inflatable portable sign for serving as a roadway marker, hazard indicator, real estate sign, and the like consisting of a supporting post having one end sharpened for insertion into the ground and supporting an air valve on the opposite end, a balloon having a desired sign imprinted thereon detachably affixed to the opposite end of the air valve, and an air source attached to an air intake portion of the valve for inflating the balloon sign to the desired diameter at which time the valve is closed to retain the balloon inflated. In addition, the support rod is provided with a projection adapted to be engaged by a lifting handle of a jack supported on the ground to effect the removal of the post from the ground upon completion of use of the sign.