PURPOSE: To ensure a seal effect and to reduce the given space of a device, by a method wherein a powdery material, such as peat, under an atmospheric pressure is fed in a container in a condition to hold the pressure of a pressure container, and given sealing function can be provided through a simple mechanism.

CONSTITUTION: A powdery material feeding device is provided with a feed hopper 13 for a powdery material under an atmospheric pressure, a duct 17 running between the hopper and an inlet 3 of a reactor 1, a pressure seal part 20 having a throttle 19 and a sluice valve 18, and means 15 and 16 which feed with a pressure a powdery material in the feed hopper 13. Thus, when the powdery material is fed with a pressure into the duct 17 with the aid of forced feeding means 15 and 16, the powdery material is pressurized with the throttle 19 throttled, and a pressure force is produced between the powdery material and the inner wall surface of the duct to firmly adhere the powdery materials to each other to reduce gaps therebetween. The powdery material must be intermittently fed with a pressure with the aid of a reciprocating plunger, but when a forced feed force on the powdery material in the pressure seal part 20 is rendered ineffective, since the pressure on the powdery material is held by closing the sluice valve 18, sealing action is maintained.