A power relay assembly is provided. A power relay assembly according to an exemplary embodiment of the present invention comprises: an upper case having at least one electric element mounted on one surface thereof; a lower case coupled to the upper case; and at least one bus bar electrically connected to the electric element, disposed between the upper case and the lower case, and including a bottom portion that is in surface contact with at least one of the upper case and the lower case, wherein at least one side of the bottom portion contacts a portion made of a plastic material having heat dissipation and insulation properties in the upper case and the lower case.