Disclosed therein is a stator assembly, which includes a circular base part and a stator core having a plurality of teeth radially formed on an outer face of the base part and respectively having a tooth end portion. The stator assembly further includes: a magmate holder including a base plate, at least one inner leg and at least one outer leg formed at a lower portion of the base plate, and a power connector part formed on an upper portion of the base plate and having a joining projection formed at one side thereof; and a sensor cover including a body part and a hook formed on a lower portion of the body part and being joined with the joining projection.