A fan introduces air and send the air toward an air blow target. The fan includes an impeller and a casing. The casing includes a first wall covering the impeller, a second wall covering the impeller and facing the first wall, and a peripheral wall surrounding the impeller and connecting the first and second walls. The peripheral wall has an air discharge port for discharging air toward the air blow target. The impeller is located between the first wall and the second wall. The second wall is located closer to a side cover than the first wall is. At least the first wall or the second wall has an air inlet port for introducing air into the casing. The outside air inlet is located at a different position from the air inlet port as viewed from a facing direction in which the fan and the side cover face each other.