Abstract: An object of the present invention is to provide a bearing device which includes a lubricant supply device that is capable of supplying lubrication oil from a lubrication oil tank to a rolling bearing without time lag and without using a pump, and at a high level of energy efficiency. A bearing device is constituted by a rolling bearing and a lubricant supply device combined with each other. The lubricant supply device includes a lubrication oil tank which stores pressurized lubrication oil and has a lubrication oil discharge spout; an open/close valve which opens/closes the discharge spout of the lubrication oil tank; a driving section which operates the open/close valve; and an electric power source section which generates electric energy for operation of the driving section. The lubricant supply device is attached to the rolling bearing or to a spacer adjacent thereto.