1. A friction drive belt comprising a compression rubber layer which is provided on an inner periphery of a belt body and transmits power between pulleys upon coming into contact with the pulleys, wherein the compression rubber layer includes a surface rubber layer having numerous pores on a pulley contact surface, and an inner rubber layer which is provided toward an inside of the belt relative to the surface rubber layer and whose storage modulus at 25° C. in a belt length direction is higher than that of the surface rubber layer and is in the range from 30 to 50 MPa.