The personal networks of elderly people tend to decline as they become older, however, if they are dog promotes healthy aging and is a positive stimulus for the growth of personal networks in the community. owners, social relationships are stimulated through dog walking. To clarify whether dog owner’s personal networks sustain growth quickly and easily, we monitored and compared the network structures, which were created by “dog walking” and “other” activities such as neighbors chatting and community circles. The subject locations were situated 2kms radius of residential area in Tokyo. The participant was a healthy dog owner, 68 years old, who resided in the area and who, for her dog walks, often used a river centrally located in the area. The surveys were performed at 6 month intervals; with the first survey submitted 3 months after the participant started her dog walking activities. Four surveys were done between March 2004 and March 2006. A P.D.M(Psychological Distance Map) was used to create her networks, We analyzed network size, network density, strength of the relationship. As a result ; 1)Over time, the “dog walking” network expanded four fold from the first survey. The other networks (community circles and neighbors chatting) didn’t illustrate significant changes over the same period and were always smaller than the “dog walking” network. 2) Over the two years of surveys, both of the network’s densities maintained the same ratios regardless of fluctuating size. The “dog walking” network density ratio was ten times lower than the “other” networks. Even if the number of the “dog walking” network ties and members increased, the density ratio remained constant. 3) The strength of the “dog walking” relationships varied. Almost half of the members had “weak ties”4). The number of the members having stronger ties did increase. Over half of the original members, who had weak ties in the beginning, built strong relationships over the period of this study. The results of this study indicate that, “dog walking” stimulates growth of new members, and strengthens interpersonal relationships in the community. We confirmed that “dog walking” networks expand quickly compared with other personal networks. The relationships between new members are usually very weak at first, but the relationships become stronger quickly. In this case study, we found that the function of “dog walk.