PROBLEM TO BE SOLVED: To provide a food material mixing apparatus capable of easily cleaning an air-discharging passage for discharging exhaust cooling air from a mixing drum, to the outside of a machine frame.SOLUTION: A mixing drum supported on a machine frame rotatably around an axial core for drum rotation in a horizontal direction comprises: a drum body having the upper side thereof opened and a drum cover for covering the opened upper side of the drum body. Drum shafts are provided on both sides of the drum body, the drum shaft has a cylindrical shape with its shaft center as the axial core for drum rotation and is communicated with an inside space of the mixing drum. The food material mixing apparatus is configured such that cooling air is supplied from one drum shaft into the mixing drum but is discharged from the other drum shaft. A discharging box having a discharged air-entering port and a discharge port is detachably provided on the machine frame, the discharging air-entering port is connected with the drum shaft on the discharging side and takes in the cooling air discharged from the mixing drum, and the discharge port discharges the cooling air taken in from the discharged air-entering port, to the outside of the machine frame.
