To provide a gas feeding device capable of uniformly dehumidifying and drying a powder and granular material by uniformly feeding a gas such as dry air to the powder and granular material to be fed, in a powder and granular material feeder.

In a gas feeding device in a powder and granular material feeder for continuously supplying and discharging a powder and granular material 3 supplied to an upper cylindrical hopper 11 downward by a powder and granular material feeder disposed at a lower section of the cylindrical hopper 11, a gas supply opening 20 is formed on a top face 1a of a bottom plate 1' of a lower face of a boss of a rotary blade 8 of the powder and granular material feeder to supply a gas to a space S between the top face 1a of the bottom plate 1' of the powder and granular material feeder and a lower face of the boss. An annular sheeting 22 is formed on the lower face of the boss at an outer side with respect to the supply opening 20, and the gas supplied to the space S from the supply opening 20, can be radially fed into the powder and granular material feeder through slits 23, 24 formed along the annular sheeting 22.