A new reaction apparatus including a capillary having an inner surface to which a probe molecule that specifically binds to an analyte is immobilized, allowing a short throughput time for completing the binding reaction, and achieving a highly efficient reaction using a small amount of a sample and a process of the reaction are provided. The reaction apparatus includes a capillary having an inner surface to which a probe molecule that specifically binds to an analyte is immobilized; a columnar magnetic body that is disposed in a fluid containing the analyte in the state that the fluid is placed in the capillary; end-fixing means for fixing one end of the columnar magnetic body in the capillary by a DC magnetic field; and end-moving means for moving the other end of the columnar magnetic body by an AC magnetic field so as to transfer the fluid.