Assuming a stellar magnetic dipole-field which aligns particles in the stellar atmosphere the observed polarization of the light of µ Cephei can be explained. The spatial orientation of the rotational axis, the angle between the magnetic axis and the rotational axis and the period of rotation were derived from the observational values. The period of rotation amounts to about 1650d ± 100d. In case aligned graphite flakes are present in the outer layers of the stellar atmosphere the calculated degree of polarization amounts to about 1.5 %. According to the chemical composition of the atmosphere it is more probably that siliciumcarbide particles cause the polarization. In this case the degree of polarization amounts to approximately 0.75%. The portion of polarization originating in interstellar space was estimated to Pi ≈0.8% and the position angle is about Θi ≈45°.