A motor device includes a main body, an assembling body, a stator and a rotor. The main body includes a first bearing hole and a plurality of first connectors, and all distances between each of the first connectors and an axle of the first bearing hole are the same. The assembling body has a second bearing hole. The stator includes a passage and a plurality of second connectors, the second connectors are coupled to the first connectors respectively to have the stator assembled in the main body, and the passage and the first bearing hole are coaxial. The rotor is disposed inside the passage and two ends of the rotor are installed in the first bearing hole and the second bearing hole respectively. By having both the stator and the rotor positioned by the main body, a gap between the rotor and the stator can be maintained consistently.