To provide the control device of a mobile crane in which an automatic vehicle body level control device and an automatic overloading prevention device are related with each other in a mobile crane provided with these devices.

The control device of a mobile crane is provided with an adjuster 30 which is connected to an automatic vehicle body level control device 10 and an automatic overloading prevention device 20 so that signals can be transmitted and received from each other, counts time after operation start signals from an operation start switch 11 are received and, when the automatic vehicle body level control device 10 does not complete the level extension control before the integrated time reaches a specified limit, transmits signals to the automatic overloading prevention device 20 so as to stop the operation of an actuator.