A heat dissipation device includes a radiator, a first tank, and a pump assembly. The radiator cools liquid and extends in a first direction. The first tank is connected to the radiator, and the liquid passes through the first tank. The pump assembly is connected to the first tank and circulates the liquid flowing in from the first tank. The radiator includes a pipe through which the liquid passes. The pipe extends along the first direction. The pump assembly is located on one side in the first direction of the radiator. The pump assembly includes a first pump, a second pump, and a flow path portion. The first pump feeds and circulates the liquid. The second pump feeds and circulates the liquid. The flow path portion guides the liquid fed from the first pump and the second pump toward an outside of the pump assembly.