A liquid ejection head includes a liquid ejection substrate having an ejection port surface, a support substrate for supporting the liquid ejection substrate, having two first positioning portions being in contact with an attaching portion, to which the liquid ejection head is attached, to determine the position of the liquid ejection head with respect to the attaching portion in a predetermined direction, and a housing for supporting the support substrate, having a second positioning portion being in contact with the attaching portion to determine the position of the liquid ejection head with respect to the attaching portion in the predetermined direction. A surface perpendicular to the ejection port surface and extending along the predetermined direction, having the second positioning portion, is disposed between two surfaces perpendicular to the ejection port surface and extending along the predetermined direction, each having one of the first positioning portions.