To provide a power transmission belt that improves flexure fatigue and low fuel efficiency (both bending rigidity and slidability) while maintaining lateral pressure resistance and durability without excessively increasing rubber hardness.

The power transmission belt includes: an adhesive rubber layer 1 including core cords 2 embedded in the longitudinal direction of the belt; a compressed rubber layer 3 formed on one surface of the adhesive rubber layer; and an expanded rubber layer 4 formed on the other surface of the adhesive rubber layer. At least the compressed rubber layer 3 comprises a rubber component (chloroprene rubber, etc.) and a short fiber (aramid short fiber subjected to adhesive treatment, etc.). Relative to 100 pts.mass of the rubber, the ratio of fatty acid amide may be about 0.5-10 pts.mass, and the ratio of the short fiber may be about 10-40 pts.mass.