PURPOSE: To prevent the generation of noise caused by collision by forming an outside tooth surface into all arc shaped face so as to make the teeth of a link slide into the teeth of a sprocket at the time of engaging the link.

CONSTITUTION: At the time of engaging a silent chain to which a number of links 1 are linked with a sprocket, when, e.g., the sprocket 10 is rotated in the arrow direction to engage the links 1 having the holes 2, 3 of the silent chain with the sprocket in order, as a preceding link comes to rest with respect to the sprocket, the following link is revolted centering around O' and, further the next but one link 1 is equally revolved and a link tooth 4 enters between the teeth 11a and 11b of the sprocket. At this time, due to the property of the arc shaped curved face of an inside tooth surface 7, the inside tooth face 7 is slidingly brought into contact with the teeth surface of the sprocket while making the link tooth 4 slide in between the teeth 11a, 11b. Hence, the noise of the chain caused by the collision of the link and sprocket can be prevented.