An electronic device includes a casing and a centrifugal blower. The casing includes a bottom cover and a top cover. A sidewall extends from the bottom cover towards the top cover. The centrifugal blower is surrounded by the sidewall and includes a supporting member mounted to the bottom cover, and an impeller rotatablely supported by the supporting member. The impeller includes a hub and a plurality of blades extending outwardly from the hub. Outer portions of the blades extend beyond the supporting member along a radial direction of the hub. Inner portions of the blades have a height gradually increasing along an outward direction. The outer portions have a height equal to a maximum height of the inner portions. Bottom faces of the outer portions of the blades are located below a top surface of a base plate of the supporting member.