Provide a converging mirror-based furnace for heating a target by way of reflecting from a reflecting mirror unit the light emitted from a light source and then irradiating a target with the reflected light, wherein said target-heating converging-light furnace is such that: the reflecting mirror unit comprises a primary reflecting mirror and secondary reflecting mirror; the light emitted from the light source is reflected sequentially by the primary reflecting mirror and secondary reflecting mirror and then irradiated onto the target; and the light reflected by the secondary reflecting mirror and irradiated onto the target surface is not perpendicular to the target surface. Based on the above, a system that uses converged infrared light to provide heating can be made smaller while keeping its heating performance intact, even when the system uses a revolving ellipsoid.