PURPOSE: To make the operation of the jib fixing device for a hydraulic deck crane by using the oil pressure of the oil pressure generation device of a jib crane.

CONSTITUTION: In an jib fixing device for a hydraulic deck crane, a jib 9 is provided with a hydraulic cylinder 30, in which an engaging piece 37 having an engaged hole 37a is provided on a jib rest 2, and a wedge 33 engaged/ disengaged with/from the engaging hole 37a of the engaging piece 37 is fitted to the tip of a cylinder rod 31, and a limit switch 34 detecting a condition where the wedge 33 is engaged/disengaged with/from the engaging hole 37a, and the hydraulic cylinder 30 is operated by the pressure oil of an oil pressure generation device used for rotating and winding, etc., of a jib crane 7. This shortens the piping length of oilpressure piping and the wiring length of a signal wire compared with a former device, and also eliminates electrification failure due to slipring interposing.