Abstract: This invention is related to a power transmission belt comprising a bottom rubber layer comprising an elastomer, wherein the bottom rubber layer satisfies the relation represented by the following formula (1): X/Y≧2.5  (1) in the formula, X is the change in mg in the weight of said layer after 500 wear cycles under a load of 500 grams in Taber's abrasion resistance test with a sand paper (C1500) having a particle size of 10 &mgr;m as the counter material and Y is the area in cm2 of contact between said counter material and the rubber face of the belt.