We present a systematic change of the magnetic domain Structure with temperature in epitaxial ferromagnetic MnAs film on GaAs (0 0 1), observed in a wide temperature range of 15-45 C by magnetic force microscopy. Interestingly, it is found that, as temperature increases, the domain structure within the ferromagnetic alpha-MnAs stripes shows a mixture of head-on and simple domains at 15 C and then, takes a complete transition to simple ones above 15 C. This change could be understood by change in the demagnetizing factor of the cross-section of the ferromagnetic stripes with temperature. (C) 2008 Elsevier B.V. All rights reserved.