the embodiment the head substrates 12a 12b can prevent uneven concentration due to uneven pressure in the principal scanning direction on the thermal recording paper 30 against the platen roller 29 by warping in this embodiment relating to the coefficients of thermal expansion of the head substrates 12a 12b cooling plates 19a 19b and support plate 20 u03b1 u03b1a u03b2 u03b1d u03b3 u03b1d the materials are selected so as to satisfy the relation of but the materials are not limited to fe ni alloy but cu w alloy or ti alloy for example jis h 4600 may be used in this embodiment it is intended to control the distance u03b42 of the heating resistance elements 13a 13b at the outermost end parts on the head substrates 12a 12b shown in fig4 at less than the alignment pitch u03b43 of the heating resistance elements 3 as a result of the thermal head 11 of this embodiment as far as the distance u03b42 of the heating resistance elements 13a 13b is less than the alignment pitch u03b43 of the heating resistance elements 13 the white stripe white out in thermal printing is not so obvious and it is found to be obvious when becoming about 50 u03bcm exceeding the alignment pitch u03b42 for example 40 u03bcm if the distance of 4 between the heating resistance elements 13a 13b and the respective outermost end parts of the head substrates 12a and 12a and the separation between the end faces 31a 31b is about for example 10 u03bcm respectively white stripe is not so obvious until the separation between the end faces 31a and 31b.