To provide a silent chain transmission device capable of preventing occurrence of vibration and noise.

In this silent chain transmission device, (A) a profile shape of a row of teeth when extending a silent chain linearly (1) is the same shape as a rack tooth shape having small pressure angle on a dedendum side more than a pitch line and (2) is a smooth curved line connected smoothly with a tooth shape on the dedendum side and protruding outward on the dedendum side more than the pitch line and (B) a tooth shape of a sprocket is a tooth shape formed by gear cutting by a rack having the same tooth shape as the profile shape of the row of teeth when extending the silent chain linearly.