The behavior of the magnetic moment at the tip end of the magnetic force microscope (MFM) was investigated by using two types of tip: iron wire and iron coated. MFM images of a magnetic head obtained by these two tips show quite different features. These differences were explained by assuming that the magnetic moment of the iron wire tip is almost fixed along the tip axis, while that of the iron coated tip follows the external field. In addition, it was found that the moment of the iron coated tip can respond to an ac excited head field of up to 50 MHz.