other than the airflow generating area 25 moreover the extending direction of the radiating fins 14 direction a is tilted toward the low density area 23 rather than the airflow generating direction direction c the pressure loss of the high density area 22 increases compared to that of the low density area 23 when airflows having the same flow rate flow downward due to the difference between arrangement densities of the radiating fins 14 a radiating method using the heat sink 1 is described below while setting the heat sink 1 formed as described above into the housing 3 of the personal computer 2 as shown in fig4 the personal computer 2 is operated and simultaneously the blasting fan 8 is driven the cpu 5 generates heat when the personal computer 2 is operated and the heat is conducted to the radiating plate 10 and radiating fins 14 through the cpu contact portion 14 contacting the cpu 5 moreover because the blasting fan 8 is driven airflow is generated in the direction c in fig1 from the nozzle 18 of the blasting fan 8 in this case the high density area 22 to which the airflow is directly blasted in the duct like structure 17 becomes a high pressure and the low density area 23.