A thermal printer head comprises an array of heating elements (1-1.about.1-N) mounted on an insulating base member (20). Each of the heating elements is connected to a common voltage source (V) and has a temperature dependent electrical resistance. Electrically resistive elements (2-1.about.2-N) are respectively connected in series with the heating elements to form a plurality of series circuits. Current supply circuits (3-1.about.3-N, 4-1.about.4-N, 5, 6, 7-1.about.7-N, 14) are provided corresponding respectively to the resistive elements for selectively supplying a current to the series circuits in response to a sequence of print signals. A control circuit (8-11, 14) makes a determination whether a voltage developed across each resistive element is higher or lower than a prescribed threshold value and causes one of the current supply ciruits corresponding to the resistive element to control the current depending on the determination.