To provide a mobile crane capable of preventing the breakage of a mast by suppressing a lateral load generated by a mast back stop device to a lattice mast.

The mast back stop device 15 for the mobile crane comprises a hydraulic cylinder 17, a hydraulic pump 18, a solenoid switching valve 19 disposed between the hydraulic pump 18 and the hydraulic cylinder 17, a controller 22 controlling the solenoid switching valve 19 according to the detection result of a pressure detector 21, and a cylinder pressure control valve 28 releasing pressure oil exceeding set pressure. Between the solenoid switching valve 19 and the hydraulic cylinder 17, a first accumulator 23 preventing the inner pressure of a cylinder side circuit 20 from exceeding mast breaking pressure Px during the switching of the solenoid switching valve 19 is installed.

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