Noncontact atomic force microscopy (NC-AFM) is a useful tool which has an atomic resolution applicable to many fields such as surface science. It is very important to understand the interaction on hydrogen atoms and silicon surface, when we deepen the knowledge as the surface treatment and semiconductor materials of a nano scale. Therefore, the hydrogen terminated silicon surfaces have been actively studied as the most important fields of surface physics. In the previous experiment, we succeeded in the NC-AFM imaging of individual hydrogen atom on the Si(100)2x1:H monohydride surface. Thus, the NC-AFM is suitable for the observation of the hydrogen terminated silicon surface. In this paper, we investigate how the NC-AFM images the Si(100)1x1:2H dihydride surface. As a force sensor, we used a clean silicon tip. The image with the 1x1 structure was observed when the tip was relatively far from the sample. When the distance between the tip and the sample became closer, the 2x1 structure where the bright line and the dark line were alternately located was observed. Furthermore, when the tip became closer, the 1x1 structure was again appeared. It is considered that the attractive interactions between the tip and the sample changed with the change of the distance between the tip and the sample. When the tip is relatively far from the sample, the 1x1 structure of the original dihydride surface is imaged because of less the attractive interaction. However, when the tip approaches the sample, the attractive interaction between the tip and the sample becomes stronger and hence the structure of dihydride surface changes. It turns out that the Si(100)1x1:2H dihydride surface changes by the attractive interaction between the tip and the sample in NC-AFM.