A positioning structure configured to position a liquid jet head to a head installation part of a liquid jet recording device, the positioning structure comprising: a protruding part arranged to be provided to one of the head installation part and the liquid jet head; and a positioning mechanism arranged to be provided to the other of the head installation part and the liquid jet head, and configured to adjust a position of the head installation part in a direction (X, Y) along an installation surface thereof with respect to the protruding part, wherein the positioning mechanism includes: a contact member configured to have contact with the protruding part; and characterized in that the positioning mechanism includes a displacement mechanism configured to displace the contact member along a displacement axis extending in an oblique direction crossing a direction perpendicular to the installation surface, and at least one of contact parts (41, 81) of the protruding part and the contact member is formed to have a curved surface shape taking a first intersecting axis crossing the installation surface as a central axis, and another of the contact parts (81, 41) is formed to have a curved surface shape taking a second intersecting axis as a central axis, the second intersecting axis crossing an imaginary plane including the displacement axis and a vertical axis extending in a direction perpendicular to the installation surface, and the second intersecting axis being nonparallel to the first intersecting axis. a protruding part arranged to be provided to one of the head installation part and the liquid jet head; and a positioning mechanism arranged to be provided to the other of the head installation part and the liquid jet head, and configured to adjust a position of the head installation part in a direction (X, Y) along an installation surface thereof with respect to the protruding part, wherein the positioning mechanism includes: a contact member configured to have contact with the protruding part; and characterized in that the positioning mechanism includes a displacement mechanism configured to displace the contact member along a displacement axis extending in an oblique direction crossing a direction perpendicular to the installation surface, and a contact member configured to have contact with the protruding part; and characterized in that the positioning mechanism includes a displacement mechanism configured to displace the contact member along a displacement axis extending in an oblique direction crossing a direction perpendicular to the installation surface, and at least one of contact parts (41, 81) of the protruding part and the contact member is formed to have a curved surface shape taking a first intersecting axis crossing the installation surface as a central axis, and another of the contact parts (81, 41) is formed to have a curved surface shape taking a second intersecting axis as a central axis, the second intersecting axis crossing an imaginary plane including the displacement axis and a vertical axis extending in a direction perpendicular to the installation surface, and the second intersecting axis being nonparallel to the first intersecting axis.