Magnetic domains in (YGdBi)(3)(GaFe)(5)O-12 magnetic garnet have been studied using magnetic force microscopy (MFM). MFM results have demonstrated that the undisturbed magnetic domain structure in the garnet could be obtained with a soft magnetic tip. It is further observed that the stray field emanating from a hard tip could magnetize the low-coercivity garnet and alter the widths of the domain region. In addition, when an external magnetic field is applied to the garnet, a sequence of variations of the magnetic domain configuration in the garnet is clearly identified. The discussions on the effect of magnetic tip of MFM on magnetic domains and the external field on magnetic tips will also be presented.