NOVELTY - Apparatus for processing livestock by-product, comprises reacting tank (10) which has an inlet (11) and an outlet (12), mixing unit (20) containing blade (22) connected to a horizontal rotation axis (21) in the reacting tank, driving unit (30) which drives the blade of mixing unit, air supplying unit (40) which supplies the air into the reacting tank, warm water supplying and circulating unit in which the warm water is supplied, and discharging unit (60) which discharges the gas generated in the reacting tank.    USE - The apparatus is useful for processing livestock by-product for producing organic material compost.    ADVANTAGE - The apparatus produces high quality organic material compost, and maintains constant temperature throughout the reaction in reaction tank.    DETAILED DESCRIPTION - Apparatus for processing livestock by-product, comprises reacting tank (10) which has an inlet (11) and an outlet (12), mixing unit (20) containing blade (22) connected to a horizontal rotation axis (21) in the reacting tank, driving unit (30) which drives the blade of mixing unit, air supplying unit (40) which supplies the air into the reacting tank, warm water supplying and circulating unit in which the warm water is supplied and circulated to surround the lower portion of reacting tank, and discharging unit (60) which discharges the gas generated in the reacting tank, where the reacting tank is divided into a first reacting tank (13) of one side and second reacting tank (14) of the other side by a portion wall (15), which has a warm water jacket (17) surrounded by an insulation wall (16) at the lower portion of first reacting tank and second reacting tank. The second reaction tank has a penetration flow line hole (151) at the portion wall, and an opening and closing door unit (18) at the penetration flow line hole, and opening and closing door unit, helical axis (182) is connected rotatably to the upper portion of semicircular door panel (181) having opened lower portion, a handle (183) connected to the upper portion of the helical axis, and the helical axis is screw-connected to a helical axis guide (184) formed in the portion wall.    DESCRIPTION OF DRAWING(S) - The drawing shows schematic view of apparatus.    Reaction tank (10)    Inlet (11)    Outlet (12)    Mixing unit (20)    Horizontal rotation axis (21)