An air blower enabling efficient cooling is provided. The air blower (1) includes: an impeller (3); and a motor (5), wherein the impeller (3) includes a plurality of first blades (32) and a cup (33) arranged at the inner periphery side d of the plurality of first blades (32), the motor (5) includes a housing (51) arranged inside the cup (33), a stator (73), and a rotor (52) arranged inside the stator, and an outer peripheral surface (41c) of the cup (33) is provided with an opening part (43) facing an outer peripheral surface (51c) of the housing (51).