Abstract: A planar heating device for a mirror. The device comprises a glass film 18 formed on a metallic chrome film 16b on the back side of the mirror; a group of electrodes formed on the glass film, the group including main electrodes 3, 4, power terminal lead electrodes 5, 6 and sub-electrodes 7, 8; a resistance film 9 formed so as to cover the sub-electrodes; an electrically insulating film 20 formed on the resistance film 9 and the group of electrodes; and power terminals 11, 12 or power lead lines soldered to the respective power terminal lead electrodes 5, 6. The glass film 18 is formed directly on the back side of the mirror by screen printing or a spray process. The group of electrodes and the resistance film 9 are formed directly on the back side of the mirror by screen printing. Silver electrically conductive ink having inorganic glass as binder is used as a material for the group of electrodes.