Abstract: An infrared thermal lamp, which has a filament mounted to the lower end of a support rod downwardly extending from a stem of a base, is disclosed. The infrared thermal lamp includes an insulating plate having an anchoring slot at the center for receiving the lower end of the support rod in a semi-melted state. Thus, the insulating plate is fixedly mounted to the support rod, and the anchoring slot is opened at the top end and is closed at the bottom end and has an enlarged diameter at the bottom end, thereby improving productivity, saving labor, automating the mounting process of the insulating plate, and reducing production cost.