A method and system to provide a blog by using a mobile terminal, and a mobile blog (MB) caster therefor, the method including: receiving blog data including one or more pieces of downsized data from an MB caster; selecting a piece of downsized data from among the one or more pieces of downsized data; obtaining metadata corresponding to the selected piece of downsized data; accessing a web blog server; and downloading original data corresponding to the metadata from the web blog server. Since the blog is created and provided by using the downsized data, instead of the original data, a blog server operation can be realized by using only existing mobile devices. Furthermore, the mobile terminal does not have to be connected to the Internet (or the web blog server) for a blog service. Also, it is possible to provide the blog at very high speed.