Social Media use has become widespread in recent years. This paper investigates whether there is a regional difference in social media use. The author focuses on the relationships between using social media and child-rearing support networks. In order to understand the relationships, the author conducted a questionnaire survey via the internet. Analyses of 723 responses received from women aged 18 to 39 living in Kanto region who were rearing children revealed the following 3 findings. 1） In less urbanized areas, social media tended to be used for maintaining ties among families, relatives or people living in the local community. 2） In more urbanized areas, there was no significant relationship between social media usage and support networks. 3） In highly urbanized areas, social media usage had the closest relationships with support networks and tended to contribute to the construction and maintenance of more diverse social networks.