Liquid ejection head

A liquid ejection head comprising:

• a substrate;
• a heat generating resistor element arranged on the substrate to generate thermal energy for ejecting liquid;
• and a flow channel forming member for forming a flow channel for allowing liquid to flow therethrough, the flow channel forming member having a side wall surrounding at least part of the heat generating resistor element,
• the heat generating resistor element having a pair of oppositely disposed sides, a pair of electrical connection regions being formed on the substrate-facing surface of the heat generating resistor element in order to supply electric energy to the heat generating resistor element, the electrical connection regions extending along respective sides of the pair of sides and separated from the respective sides of the pair of sides by a distance,
• the heat generating resistor element having at least one convex corner located outside of the electrical connection regions in an extending direction of the electrical connection regions and also in a direction intersecting the extending direction, the convex corner being rounded or chamfered, and
• the side wall having at least one concave corner facing the at least one convex corner, the concave corner being comprised of a curved surface or a surface extending obliquely to the pair of sides.