An impeller includes an impeller cup and a plurality of blades. The impeller cup is hollow and generally cylindrical and has a lid. A housing is formed to enclose the impeller from the outside thereof. The housing has a wall defining a passage of an airflow generated by rotation of the impeller. At axial ends of the passage are formed an air inlet and an air outlet, respectively. The wall is provided with an air-inlet side portion which has an inner diameter increasing toward the air inlet. An axially upper end of a radially outer edge of each blade axially projects toward the air inlet beyond the lid of the impeller cup, and is located to be covered by the air-inlet side portion when seen from the outside in the radial direction. An axially upper end of a radially inner edge of each blade is located on a base portion side of the lid of the impeller cup. An axially upper edge of each blade is at an angle with respect to the axial direction so as to get close to the base portion in a direction from the radially outer edge of each blade to a radially inner edge.