PURPOSE: To form a small thermal head with a high productivity and a high reliability by making a common conductor out of a metal foil.

CONSTITUTION: An opening 4a of an insulation layer 4 is filled with a conductor by a method such as thin film technique to form a through hole conductor 6 through which a common conductor 5 makes electrical connections with a plurality of common electrodes 3a. The common conductor 5 is made out of a metal foil such as copper and aluminum and can prevent concentration of current and disconnection by easily increasing the thickness thereof, overcomming any large current flow therethrough 5 as caused by generating heat in a number of resistors 2 of a thermal head while enabling the miniaturization of the thermal head by reducing the width of thereof 5. This also permits complete separation of the formation process of the common conductor 5 made out of the metal foil from the formation process of an electrode conductor 3, an insulation layer 4 and the through hole conductor 6 improving the productivity. The through hole conductor 6 is not required if a solder or a conductive adhesive is imbedded into the opening 4a of the insulation layer 4 to connect the common conductor 5 to the common electrodes 3a.