PURPOSE: To prepare roasted coffee beans, flour, etc., having a good taste by employing a roaster having a ceramic layer on the inner surface of a roasting container disposed in the roaster.

CONSTITUTION: A ceramic layer 13 is formed by a ceramic-processing method on the inner surface of a roasting container 2 comprising a semi-cylinder 3 at the lower portion, an upper container 4 opened in the upper direction and an opening portion 5 formed on the upper surface. The first ceramic net 14 and the second ceramic net 15 are disposed between a hot air inlet 12 and burners 11 attached to a roaster 1 below the roasting container 2 and hot air containing far IR rays is generated. A stirring shaft 19 equipped with discharging blades 17 for discharging roasted materials from a discharging outlet and with a doglegged-shaped stirring blades 18 is further disposed in the roasting container 2 to readily stir and discharge the roasting materials.