The present invention provides an inexpensive heater exhibiting good gas-tightness, as well as a method for manufacturing the same. The heater includes a cylindrical metallic shell having a through-hole with a heating element disposed in the through-hole such that a portion projects from one end of the shell. The heater is adapted to generate heat upon application of electricity thereto. A rod-like axial member has a coil lead for electrically connecting a portion of the axial member and the heating element. A gas-tight seal member formed of an insulating polymeric material is interposed between the axial member and the inner surface of the through-hole in such a manner to surround the outer circumferential surface of the axial member. A crimped portion of the metallic shell brings the gas-tight seal member into close contact with the outer circumferential surface of the axial member and the inner wall surface of the through-hole form a gas tight seal.