A method of providing a Social Networking Service (SNS) based on a phone book of a mobile terminal is provided. The method includes executing the phone book, receiving a selection of a group tab of the phone book from a first user of the mobile terminal, displaying a list of social groups that shares group activity information of its group members including a second user registered in the phone book in response to the selection of the group tab, and, when at least one social group is selected from the list of social groups, providing at least one piece of information from among group information, a group share space including group activity information, and link information corresponding to the selected at least one social group.