COOLING SYSTEM

A cooling system for cooling a fuel cell on a vehicle includes a radiator, a branch portion connected to an outlet side of the radiator, a confluence portion connected to an inlet side of the radiator, a first passage and a second passage connected in parallel between the confluence portion and the branch portion, a fuel cell and a first pump provided in the first passage, a resistor and a second pump provided in the second passage, and a backflow preventer provided in the second passage. The first passage has no backflow preventer.