Provided is a silent chain that enables adjustment of the stiffness and balance of stiffness between upper and lower sides of guide plates, that prevents long pin failure resulting from deflection ortorsional deformation while securing a sufficient area and strength for the portion contacting a side face of a sprocket, and that suppress vibration and fluctuation. The upper end of a lightening hole (112) of the guide plate is positioned above a pitch line (P), and a lower end of the lightening hole (112) extends out beyond lines that connect intersections T between inner side edges of front and rear pin fitting holes (111) and the pitch line P, and a midpoint C1 of a lower end edge of the guide plate (110) in a front to back direction. Outermost portions of the lightening hole (112) in a longitudinal direction are formed within a range that does not go beyond a pair of vertical lines V vertical to the pitch line passing through the intersections T.