A solder device includes a light source, a solder module, an optical guiding assembly, a sensor and a feedback controller. The light source emits waveband light guided to a to-be-soldered area for heating. The optical guiding assembly is disposed between the light source and the solder module, and the waveband light is guided to the solder module by the optical guiding assembly. The sensor is disposed on another side of the optical guiding assembly for receiving a sensing light beam and then generating a sensing signal. The sensing light beam is guided to the sensor by the optical guiding assembly. The feedback controller is connected with the sensor and the light source for receiving the sensing signal and then controlling the light source. The optical guiding assembly, the sensor and the feedback controller are integrated as a system controller. Therefore, the volume and weight of the solder module are compacted.