A membership social network system includes a processor configured to select a picture type among a plurality of picture types, and to, according to parameters, change a tone of original image data, which is uploaded from a member terminal to a server, to a tone of a selected picture type, a browse controller configured to make a tone-changed image data, which is created by the processor, browsable on the member terminal, and a grouping module configured to group a member who uploads the original image data and a member who creates the tone-changed image data.