An indoor antenna has a base panel, a coax cable panel, a coax cable, a panel cover, and a hole cover. The coax cable panel is combined with the base panel. The coax cable is electrically connected with the coax cable panel and is connected with a plug. The panel cover is combined with the base panel, shelters the coax cable panel and has a cover through hole inserted through by the coax cable. The hole cover is mounted in the cover through hole of the panel cover and has a coax cable recess inserted through by the coax cable with the plug. Therefore, when the indoor antenna is assembled, the coax cable with the plug can be inserted through the cover through hole, and the indoor antenna can be assembled smoothly and modularized easily.