A cooling device includes, a liquid immersion tank having an opening in a top thereof, in which an electronic circuitry including a heat generating circuit is immersed in a second coolant, a lid fitted into the opening, and a cooler, into which a cooled first coolant is input through a first pipe, and from which the first coolant is output through a second pipe, the cooler being located between a liquid level of the second coolant and a lower surface of the lid that faces the liquid level.