Abstract: A micro reactor includes a filter 2 having a plurality of fine pores; a plurality of compartments 3a and 3b formed by the filter; and an element which enables a material passing through the fine pores to be transferred between the compartments, wherein the element which enables the material to be transferred between the compartments 3a and 3b can change surface tension of the material. In addition, volume of the material contained in the compartments 3a and 3b may change. In addition, the change in the surface tension of the material is carried out by selectively irradiating or not-irradiating light onto the surface thereof by using the filter 2 having a titan oxide surface. In addition, the change in the volume of the material contained in the compartments 3a and 3b is carried out by using light, heat, electricity, or magnetism.