A cooling device according to the invention includes: a first flow channel configured so that a coolant passes; a first heat receiving portion; a first heat radiating portion arranged in the first flow channel; a first heat transferring portion configured to transfer heat from the first heat receiving portion to the first heat radiating portion; a second flow channel configured so that the coolant passes; a second heat receiving portion; a second heat radiating portion arranged in the second flow channel; and a second heat transferring portion configured having a longer length than the first heat transferring portion and transferring heat from the second heat receiving portion to the second heat radiating portion. The second heat radiating portion is configured having a larger surface area than the first heat radiating portion.