To stably obtain a pyrolysis gas from a fuel supplying device for dry distillation furnace by supplying a fuel composed of a mixture of various kinds of fuels to the furnace at appropriate timing.

A fuel supplying device which intermittently supplies fuel (a) composed of a mixture of various kinds of fuels to a dry distillation furnace 04 which obtains a pyrolysis gas (c) from the fuel (a) is provided with an HC detector 07 which detects the HC concentration in the pyrolysis gas (c) produced in the furnace 04 so that the device may supply the fuel (a) based on the value of the HC concentration detected by means of the detector 07, whether or not the value reaches a peak.