An object of the present invention is to provide a silent chain and a silent chain transmission device which stabilize chain behavior during chain travel to suppress an occurrence of tooth skipping and to reduce a string vibration sound and a meshing noise with simple configurations. In a silent chain 110, a pin hole 161 of an inner plate 160 and a pair of locker pins 170 are configured in such a size that a gap is formed between a seat surface 163 and a back surface of a short pin 172 in a state where the pair of locker pins 170 are in contact with each other on rolling surfaces 171a and 172a.