PURPOSE: To prepare a fuel which is readily ignitable and emits no malodor, by performing continuous fermentation of a mixture of cattle droppings with wood powder in a rotary kiln, drying the cattle droppings with heat of fermentation and pelletizing the dried fermentation mixture.

CONSTITUTION: Cattle droppings and wood powder in an amount of about 40wt% of said droppings are fed from a hopper 24 into a rotating drum 13 of a rotary kiln 1 for mixing by rotation of the drum 13. The mixture is passed continuously from the hopper 24 to a discharge opening 25 in about 48hr by the action of fans 21 provided inside the rotary drum 13. The cattle droppings are fermented by fermenting bacteria contained in them and are dried by heat of fermentation. The dried fermentation mixture is discharged through the discharge opening 25 and is pelletized into the aimed fuel.