A sensor equipped wheel support bearing assembly for rotatably supporting a vehicle wheel relative to an automotive vehicle body, which assembly comprises: an outer member having an inner periphery formed with a plurality of rolling surfaces defined therein; an inner member having an outer periphery formed with rolling surfaces opposed to the rolling surfaces in the outer member; a plurality of rows of rolling elements interposed between those rolling surfaces (3, 4); a strain amplifying mechanism for amplifying a strain in a stationary member served by the outer member, which strain occurs when the rolling elements pass by; a strain sensor element for detecting the strain amplified by the strain amplifying mechanism; and a calculator for calculating, from an output of the strain sensor element, a load acting on the bearing assembly or a load acting between the vehicle wheel and a road surface, and that an outer peripheral surface of the outer member is formed with, at least in an axial range in which the rolling surface of the outer member lies, a thin walled area having a wall thickness smaller than that of a proximity thereof; and that the strain amplifying mechanism is provided at the thin walled area; and the thin walled area includes a groove provided in the outer peripheral surface of the outer member so as to extend axially; characterized in that the strain amplifying mechanism includes a bridge piece which straddles the groove with opposite ends of the bridge piece being secured to opposite open edge portions (23a, 23b) of the groove, and a leg piece protruding from the bridge piece and fixed to or held in contact with a bottom surface of the groove; and in that the strain sensor element is fixed to a cutout that is provided in the bridge piece. an outer member having an inner periphery formed with a plurality of rolling surfaces defined therein; an inner member having an outer periphery formed with rolling surfaces opposed to the rolling surfaces in the outer member; a plurality of rows of rolling elements interposed between those rolling surfaces (3, 4); a strain amplifying mechanism for amplifying a strain in a stationary member served by the outer member, which strain occurs when the rolling elements pass by; a strain sensor element for detecting the strain amplified by the strain amplifying mechanism; and a calculator for calculating, from an output of the strain sensor element, a load acting on the bearing assembly or a load acting between the vehicle wheel and a road surface, and that an outer peripheral surface of the outer member is formed with, at least in an axial range in which the rolling surface of the outer member lies, a thin walled area having a wall thickness smaller than that of a proximity thereof; and that the strain amplifying mechanism is provided at the thin walled area; and the thin walled area includes a groove provided in the outer peripheral surface of the outer member so as to extend axially; characterized in that the strain amplifying mechanism includes a bridge piece which straddles the groove with opposite ends of the bridge piece being secured to opposite open edge portions (23a, 23b) of the groove, and a leg piece protruding from the bridge piece and fixed to or held in contact with a bottom surface of the groove; and in that the strain sensor element is fixed to a cutout that is provided in the bridge piece.