Abstract. The combination of interval valued vague sets and rough sets is developed in this paper. The lower and upper approximation operators of an interval valued vague set are constructed, which are partitioned by an indiscernibility relation in Pawlak approximation space. Further properties associated with the lower and upper approximations of interval valued vague sets are examined. Finally, the roughness measure of an interval valued vague set is presented as an extension of the parameterized roughness measure of a vague set. Meantime, the related properties with respect to roughness measure are established and analyzed.