To provide a silencer for a powdery-granule crushing machine silencing impact sound generated at the time of crushing a powdery granule and also applicable to a small size crushing machine.

The silencer 7 for taking-in secondary air has an external air introduction part 70 formed in a circumferential direction and receiving external air; and a connection end 71 formed on an axial end. The silencer 7 is constituted by an outer pipe 74 provided with a stepped part constituted from a large diameter part 72 and a small diameter part 73; and an inner pipe 77 having an entrance connection part 75 formed so as to be opened in an axial direction, connected to a screw feeder 6, i.e. an upstream part and receiving the powdery granule, having an external air introduction passage 78 coaxially fixed to the inside the outer pipe 74 and formed between an outer diameter surface and an inner wall of the outer pipe 74, introducing the external air to the entrance connection side 75 through a communication passage 79 merging the powdery granule fed from the screw feeder 6 with it to make mixing air and transporting the mixing air to the connection end 71 side by an inner passage 80 in a reverse direction to the introduction direction of the external air.