To provide an effective operation method in a recycling furnace or a multifuel combustion furnace.

A recycling apparatus EQU comprises the recycling furnace 1 for achieving carbonization treatment or dry distillation treatment; and the multifuel combustion furnace 2 for supplying a secondary fuel as needed and burns a flammable gas being generated by the recycling furnace. The recycling apparatus EQU also comprises a means for adjusting the amount of supply of the secondary fuel, based on an outlet temperature in the multifuel combustion furnace 2; and a means for permitting the throwing of waste into the recycling furnace 1 when the amount of supply of the secondary fuel goes below a reference value SD by a specific amount of time and then goes above the reference value DS again.