Abstract: The dyadic of the molecular inertia tensor is given. The representation quadric for the inertia tensor is obtained in the light of the scalar field characteristic. The features of the quadric for the molecules of a variety of point groups are discussed on the basis of Neumann's principle. The distribution pattern of the magnitude of the molecular inertia tensor in the various directions is given, and the directions of the collinear angular momentum and angular velocity are indicated.