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 (O2) extending in an oblique direction crossing a direction perpendicular to the installation surface , and at least one of contact parts of the protruding part and the contact member is formed to have a curved surface shape taking a first intersecting axis (O1) crossing the installation surface as a central axis, and another of the contact parts is formed to have a curved surface shape taking a second intersecting axis (O3) as a central axis, the second intersecting axis crossing an imaginary plane including the displacement axis (O2) and a vertical axis (O4) 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 (O2) 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 (O2) extending in an oblique direction crossing a direction perpendicular to the installation surface , and at least one of contact parts of the protruding part and the contact member is formed to have a curved surface shape taking a first intersecting axis (O1) crossing the installation surface as a central axis, and another of the contact parts is formed to have a curved surface shape taking a second intersecting axis (O3) as a central axis, the second intersecting axis crossing an imaginary plane including the displacement axis (O2) and a vertical axis (O4) extending in a direction perpendicular to the installation surface , and the second intersecting axis being nonparallel to the first intersecting axis. <EOS>