A radial rolling-bearing testing device for performing a test of a bearing life of a radial rolling bearing, which includes an outer ring that has an inner peripheral surface, on which an outer ring raceway is formed, an inner ring that has an outer peripheral surface, on which an inner ring raceway is formed, and a plurality of rolling elements, which are provided so as to freely rotate between the outer ring raceway and the inner ring raceway, the device comprising: a rotary shaft, to which the inner ring of the radial rolling bearing is fitted on the outside; a rotational driving section, which is configured so as to rotate the rotary shaft; a lubricant reservoir, which is configured so as to retain lubricant, in which a portion of the radial rolling bearing is immersed; a load applying section, which is configured so as to apply a radial load to the radial rolling bearing; a heater, which is configured so as to maintain an oil temperature of the lubricant at a desired temperature; and a support sleeve (17a, 17b), to which the radial rolling bearing is fitted on the inside, wherein a foreign matter is mixed into the lubricant, characterized in that, a bottom surface of the lubricant reservoir is a curved concave surface with a partial cylindrical form, which is concentric to a central axis of the rotary shaft, and the heater is a plate with partial cylindrical form that is concentric to the central axis of the rotary shaft, wherein the heater is provided between the bottom surface of the lubricant reservoir and an outer peripheral surface of the support sleeve (17a, 17b), and a gap is interposed between a lower surface of the heater and a bottom surface of the lubricant reservoir, and between an upper surface of the heater and the outer peripheral surface of the support sleeve (17a, 17b), wherein a radius of a curvature of the bottom surface of the lubricant reservoir is 0.6 times or more and 2 times or less than an outer diameter of the radial rolling bearing, and wherein the heater is curved along the bottom surface of the lubricant reservoir. a rotary shaft, to which the inner ring of the radial rolling bearing is fitted on the outside; a rotational driving section, which is configured so as to rotate the rotary shaft; a lubricant reservoir, which is configured so as to retain lubricant, in which a portion of the radial rolling bearing is immersed; a load applying section, which is configured so as to apply a radial load to the radial rolling bearing; a heater, which is configured so as to maintain an oil temperature of the lubricant at a desired temperature; and a support sleeve (17a, 17b), to which the radial rolling bearing is fitted on the inside, wherein a foreign matter is mixed into the lubricant, a bottom surface of the lubricant reservoir is a curved concave surface with a partial cylindrical form, which is concentric to a central axis of the rotary shaft, and the heater is a plate with partial cylindrical form that is concentric to the central axis of the rotary shaft, wherein the heater is provided between the bottom surface of the lubricant reservoir and an outer peripheral surface of the support sleeve (17a, 17b), and a gap is interposed between a lower surface of the heater and a bottom surface of the lubricant reservoir, and between an upper surface of the heater and the outer peripheral surface of the support sleeve (17a, 17b), wherein a radius of a curvature of the bottom surface of the lubricant reservoir is 0.6 times or more and 2 times or less than an outer diameter of the radial rolling bearing, and wherein the heater is curved along the bottom surface of the lubricant reservoir.