Provided herein is a variable social network service method and apparatus. The variable social network service method includes receiving, by a variable social network service apparatus, information on whether or not a user serves as a bridge from a user apparatus of the user, and determining, by the variable social network service apparatus, whether or not to expand a social network based on the user based on the information on whether or not the user serves as the bridge, wherein the variable social network service apparatus determines whether or not social networking is possible between a first network subject of the user and a second network subject of the user depending on whether or not the user serves as the bridge.