A stator of an outer rotor type motor is provided. The stator may include a helical core having stacked layers formed by winding a single metal sheet having a predetermined shape in a helical direction, a base and teeth that protrude from the base. The stator may also include an insulator made of electrical insulation material that surrounds the helical core, recesses formed in the base of the helical core that reduce stress due to the winding of the single metal sheet and disposed under the teeth, and auxiliary recesses formed in a bottom of the recesses.