PURPOSE: To accurately measure the temp. of the recording liquid of a recording head.

CONSTITUTION: A substrate has an electrothermal conversion element 15 or the connection wiring 14 thereof and temp. sensor connection wiring 16 and these elements are covered with an insulating layer 17 and a part of the surface of the insulating layer 17 is protected by a protective layer 18 while the protective layer 18 prevents the damage of the insulating layer 17 caused by the cavitation of ink. A temp. sensor 19 is formed in a lithographic process forming the protective layer 18 by patterning the same metal film and directly comes into contact with ink to detect the temp. thereof.