A printing fluid cartridge configured to be inserted into a cartridge mounting portion in an insertion direction against a biasing force exerted in a removal direction opposite the insertion direction, the printing fluid cartridge comprising: a front face oriented toward the insertion direction when the printing fluid cartridge is inserted into the cartridge mounting portion; a rear face positioned opposite the front face with respect to the insertion direction and oriented toward the removal direction when the printing fluid cartridge is inserted into the cartridge mounting portion; a chamber positioned between the front face and the rear face and configured to store printing fluid therein; a printing fluid supply portion positioned at the front face and configured to supply the printing fluid from an interior of the chamber to an exterior of the chamber; an electrical interface (75, 76, 77) configured to allow an electrical access to an integrated circuit provided to the printing fluid cartridge, the electrical interface being positioned between the front face and the rear face with respect to the insertion or removal direction; and wherein the printing fluid cartridge is configured to be inserted into the cartridge mounting portion in an upright position, and the printing fluid cartridge in the upright position has a width in a width direction, a height in a height direction, and a depth in a depth direction, wherein the width direction, the height direction, and the depth direction are perpendicular to each other, the depth direction is parallel with the insertion direction and the height direction corresponds to the gravitational direction, characterized by an engagement portion for retaining the printing fluid cartridge in the cartridge mounting portion against the biasing force; wherein the engagement portion comprises an engagement surface which extends in the width direction (5 1) and the height direction when the printing fluid cartridge is in the upright position, the engagement surface is configured to contact an engagement member of the cartridge mounting portion, wherein a plane on which an upper surface of the electrical interface (75, 76, 77) extends, which is a plane extending in the depth direction and the width direction, intersects the plane on which the engagement surface extends. a front face oriented toward the insertion direction when the printing fluid cartridge is inserted into the cartridge mounting portion; a rear face positioned opposite the front face with respect to the insertion direction and oriented toward the removal direction when the printing fluid cartridge is inserted into the cartridge mounting portion; a chamber positioned between the front face and the rear face and configured to store printing fluid therein; a printing fluid supply portion positioned at the front face and configured to supply the printing fluid from an interior of the chamber to an exterior of the chamber; an electrical interface (75, 76, 77) configured to allow an electrical access to an integrated circuit provided to the printing fluid cartridge, the electrical interface being positioned between the front face and the rear face with respect to the insertion or removal direction; and wherein the printing fluid cartridge is configured to be inserted into the cartridge mounting portion in an upright position, and the printing fluid cartridge in the upright position has a width in a width direction, a height in a height direction, and a depth in a depth direction, wherein the width direction, the height direction, and the depth direction are perpendicular to each other, the depth direction is parallel with the insertion direction and the height direction corresponds to the gravitational direction, characterized by an engagement portion for retaining the printing fluid cartridge in the cartridge mounting portion against the biasing force; wherein the engagement portion comprises an engagement surface which extends in the width direction (5 1) and the height direction when the printing fluid cartridge is in the upright position, the engagement surface is configured to contact an engagement member of the cartridge mounting portion, wherein a plane on which an upper surface of the electrical interface (75, 76, 77) extends, which is a plane extending in the depth direction and the width direction, intersects the plane on which the engagement surface extends.