PURPOSE: To reduce the thickness and the cost of plane heating heating element, to form the element in a unit, and to achieve mass production of the elements.

CONSTITUTION: A plane heating element l comprises cylindrical heating elements 2... each consisting of positive characteristic thermistor, a pair of flat metal terminals 3, 3, and an electrically insulating coating member 5 for covering the entire body and for electrically insulating the body from the outside. Recessed parts 3b... that can lock the heating elements 2 are formed on each metal terminal 3, and the heating elements 2... are thus fixed. The electrically insulating coating member 5 is formed in an integrated manner by, for example, forming synthetic resin by means of injection, etc. As a result, it is prevented that the heating element is pushed by a flowing synthetic resin and is thus displaced, and the heating element is not moved from a point at which it is positioned. It is also prevented that the synthetic resin is infiltrated into the heating element and the metal terminal due to the pressure at the time of formation, while failure in conduction of the heating element does not occur. Fixation of the heating element can thus be simplified, while the electrically insulating coating member can be inexpensively formed in an integrated manner.