Abstract: A crane includes a jib posture retention device that retains a jib in a frontward tilt posture to a boom. The jib posture retention device includes a jib mast that holds a rope connection part at a tensioning position separate from a jib proximal end and a boom distal end backward thereof to render a jib-side support rope and a boom-side support rope linearly tensioned with the jib in the frontward tilt posture. The jib mast is shiftable to a tension form of holding the rope connection part at a tensioning position in an uprise posture and a looseness allowing form of locating the rope connection part at a looseness allowing position closer to the boom distal end than the tensioning position and closer to the jib proximal end than the tensioning position to allow the jib-side support rope and the boom-side support rope to be loosened.