To provide a cooler conforming to the principle of energy saving and convection by cleaning the air while reducing the size and stabilizing temperature fluctuation.

A cooler for cooling an object with water comprises a circulation circuit for circulating the primary cooling water through pipes 2a, 3b coupling between an object to be cooled and the coil of a radiator 1, supplying the secondary cooing water from the bottom of a water tank 2 coupled with the pipe 2a through a line pump 7 and a filter 6 and returning the secondary cooing water passed through the radiator 1, in the form of shower, from above the water tank through a shower unit 16 coupled with the pipe 2b. The water tank 3 is supplied constantly with the secondary cooling water 9 from a source through a pipe 2c and provided with a pan 17 for discharging excess secondary cooling water. The water tank and the shower of secondary cooling water are cooled by blowing the air from a fan 8.