This is the first report on observation of phase change recorded marks by use of the scanning probe microscope (SPM). The amorphous mark and crystalline blank were clearly observed by surface potential mode (SPoM) that visualized the surface potential difference among phases or materials. SPoM observation has an advantage over conventional transmission electron microscope (TEM) observation in that the sample preparation is much easier, and that amorphous mark and crystalline blank are clearly distinguished. The possibility of a novel readout method of phase change disks, and the possibility of the novel medium with a surface potential detection method are also proposed.