PURPOSE: An apparatus and a method for refining crystal grain of a material which is difficult to be processed are provided to greatly improve elongation and strength of the material and solve problems of locally nonuniformed microstructures of an existing equal channel angular pressing by deforming and refining the overall material quite uniformly. CONSTITUTION: The apparatus for refining crystal grain of a material which is difficult to be processed comprises an entry channel(10) perforated in an entry port of a forming dies(100); a shearing strain channel(20) which guides the extruded material so that crystal gain is refined by curving an extruded material(1) supplied through the entry channel(10) in an acute shearing angle (θ) with the entry channel(10); a discharge channel(30) which is curved in a certain shearing angle from the shearing strain channel(20) and discharges the extruded material(1) in a direction parallel to the entry channel(10); a main extrusion plunger(40) for forcibly pressing the extruded material(1) by a pressing means(60) at a position of the entry channel(10); and a back pressure plunger(50) for forcibly pressing the extruded material(1) positioned between the main extrusion plunger(40) and the back pressure plunger(50) at a position of the discharge channel(30) by another pressing means(60) at the same time as the main extrusion plunger(40).