Provided is a heating resistor element, including: an insulating substrate (9); a heat accumulating layer (10) bonded to a surface of the insulating substrate (9); and a heating resistor (11) provided on the heat accumulating layer (10), in which: on at least one of bonded surfaces between the heating substrate (9) and the heat accumulating layer (10), at least one of the insulating substrate (9) and the heat accumulating layer (10) is provided with a concave portion (16) in a region opposed to the heating resistor (11) to form a hollow portion (17); and the concave portion (16) has a curvature radius of 10 μm or more at each corner thereof. Accordingly, occurrence of stress concentration caused by heat or a load can be suppressed to improve durability, and both a sufficient strength and heating efficiency are realized.