The present invention relates to a pipe heater encircled conduit device (1), in which a heating element (111) wrapped with a filament (112) having high resistance is provided and a hollow quartz inner tube (113) is inserted at the outside of said heating element (113) to form a pipe heater (11), both ends of the heating element (111) being connected with an electrode pin (114) respectively. A hollow quartz outer tube (123) is inserted at the outside of the pipe heater (11), which has an inlet (121) and an outlet (122) on the tube wall. A heat transfer space (A) is thus formed between the inner quartz tube (113) and the outer quartz tube (123), and insulation members (124) are combined with the respective opening end of both tubes. By the arrangement of the inner and outer quartz tubes. (113), (123), the heat energy generated by the pipe heater (11) formed by the heating element (111) and the hollow inner quartz tube (113) can be transferred to the medium which is introduced from the inlet (121) and exhausted from the outlet (122). Thus, the medium can be heated by the heat energy generated by the heating element (111) itself by both actions of heat conduction and heat radiation.