Disclosed is an exhaust air purification device, which enables heating a carrier uniformly and heating a catalyst supported on the carrier above an active temperature thereof even when an engine is run on a cold-start mode. Specifically disclosed is an exhaust air purification device, which includes a hollow case as an exterior, a cylindrical carrier housed in the case and having a catalyst supported thereon, and a pair of electrodes arranged on the outer circumferential surface of the carrier. In the device, the carrier is electrically heated through the pair of electrodes so that the catalyst is heated to an active temperature thereof. In the device, each of the pair of electrodes is placed on an arc-shaped outer circumferential segment of the carrier that has a central angle of 20 to 40 degrees, and the electrodes are opposed to each other with the phase difference of 180 degrees.