This paper proposes a novel beam management (BM) method for integrated access and backhaul (IAB) network. From both specification and commercialization perspectives, it has been spotlighted that IAB network is promising for coverage extension of 5G wireless communication systems at millimeter wave (mmWave) frequency range. In this paper, it is shown that due to the parallelized specification works on 1) BM for access link and 2) resource allocation / topology management for backhaul link, IAB networks can be suffered from high signaling overhead for beam control. The proposed BM method can address the overhead issues (less than 10% signaling overhead is required compared with legacy system in the narrow beam scenarios) by enabling simultaneous update of activated beams across multiple component carriers in IAB networks.