A stator assembly includes a stator that opposes a rotor, which rotates about a central axis extending vertically, in a radial direction, a cover that accommodates an axially upper portion of the stator, a base portion that covers at least an axially lower side of the stator, and a circuit board that opposes the base portion in an axial direction and includes a sensor. At least one of the cover and the base portion includes a positioning portion, which is adjacent to the circuit board in the axial direction, the positioning portion being adjacent to the sensor.