An electrical thermometer comprises a metallic tip and a main body equipped with a probe portion. The front end of the probe portion is fitted into the opening of the metallic tip, which resembles a shell with a blunt end. The probe portion is formed on the main body. A thermal sensor, which is immersed and fixed in thermally conductive glue, is positioned inside the front inner end of the metallic tip. The remaining space within the metallic tip is filled up with a good thermally insulator. The metallic tip can be rapidly heated up with body temperature whenever touched, and the heat will be transferred to the thermal sensor via the thermally conductive glue. In additional, the thermally insulator can stop succeeding heat transfer.