An inkjet head comprising: a nozzle hole through which droplets are ejected in operation; a pressure chamber so provided as to communicate with the nozzle hole; and a piezoelectric device disposed on the side opposite to the nozzle hole, and arranged to cause a pressure change inside the pressure chamber, wherein a cross-sectional shape of the pressure chamber in a direction substantially perpendicular to an arrangement direction where the pressure chamber and the piezoelectric device are arranged includes a circular-arc-shaped side wall portion that has a substantially circular-arc shape on the supply side for liquid supply to the pressure chamber, and linear side wall portions connected with two ends of the circular-arc-shaped side wall portion on the side opposite to the supply side, and forming such a shape that the distance between the linear side wall portions gradually decreases toward the side opposite to the supply side, the piezoelectric device includes a displacement portion that is arranged to cause the pressure change inside the pressure chamber by displacement of the piezoelectric device, and an electrode connection portion electrically connecting the piezoelectric device and an electrode, a cross-sectional shape of the displacement portion in the direction substantially perpendicular to the arrangement direction includes a circular-arc-shaped portion that is formed inside the circular-arc-shaped side wall portion into a shape substantially equivalent to the shape formed by the circular-arc-shaped side wall portion as viewed in the arrangement direction, and has a smaller cross section in the direction substantially perpendicular to the arrangement direction than a corresponding cross section of the shape formed by the circular-arc-shaped side wall portion, the cross-sectional shape of the displacement portion in the direction substantially perpendicular to the arrangement direction further includes a linear portion that is formed inside the linear side wall portions into a shape substantially equivalent to the shape formed by the linear side wall portions as viewed in the arrangement direction, and has a smaller cross section in the direction substantially perpendicular to the arrangement direction than a corresponding cross section of the shape formed by the linear side wall portions, and the electrode connection portion is connected to the linear portion on the side opposite to the circular-arc-shaped portion in such a position as to overlap with a side wall portion of the pressure chamber in the arrangement direction. a nozzle hole through which droplets are ejected in operation; a pressure chamber so provided as to communicate with the nozzle hole; and a piezoelectric device disposed on the side opposite to the nozzle hole, and arranged to cause a pressure change inside the pressure chamber, wherein a cross-sectional shape of the pressure chamber in a direction substantially perpendicular to an arrangement direction where the pressure chamber and the piezoelectric device are arranged includes a circular-arc-shaped side wall portion that has a substantially circular-arc shape on the supply side for liquid supply to the pressure chamber, and linear side wall portions connected with two ends of the circular-arc-shaped side wall portion on the side opposite to the supply side, and forming such a shape that the distance between the linear side wall portions gradually decreases toward the side opposite to the supply side, the piezoelectric device includes a displacement portion that is arranged to cause the pressure change inside the pressure chamber by displacement of the piezoelectric device, and an electrode connection portion electrically connecting the piezoelectric device and an electrode, a cross-sectional shape of the displacement portion in the direction substantially perpendicular to the arrangement direction includes a circular-arc-shaped portion that is formed inside the circular-arc-shaped side wall portion into a shape substantially equivalent to the shape formed by the circular-arc-shaped side wall portion as viewed in the arrangement direction, and has a smaller cross section in the direction substantially perpendicular to the arrangement direction than a corresponding cross section of the shape formed by the circular-arc-shaped side wall portion, the cross-sectional shape of the displacement portion in the direction substantially perpendicular to the arrangement direction further includes a linear portion that is formed inside the linear side wall portions into a shape substantially equivalent to the shape formed by the linear side wall portions as viewed in the arrangement direction, and has a smaller cross section in the direction substantially perpendicular to the arrangement direction than a corresponding cross section of the shape formed by the linear side wall portions, and the electrode connection portion is connected to the linear portion on the side opposite to the circular-arc-shaped portion in such a position as to overlap with a side wall portion of the pressure chamber in the arrangement direction.