A cooling device includes a heat-radiating device and a centrifugal pump
provided in a closed circulation passage for circulating refrigerant. The
centrifugal pump contacts and absorbs heat from heat-generating
electronic parts by heat exchange of the refrigerant therein to radiate
the heat via the heat-radiating device. The centrifugal pump includes a
lower casing that comes into contact with the heatgenerating electronic
parts, an upper casing disposed to face the lower casing to form a pump
chamber, and an impeller sandwiched between the upper casing and the
lower casing. The lower casing includes a recessed conical surface facing
the impeller, at least one protrusion provided in a center portion of the
recessed conical surface and a contact face with which the
heat-generating electronic parts come into contact formed directly below
the protrusion on an opposite side of the recessed conical surface.