An antitheft system for the construction equipment includes a hydraulic device for controlling flow of working fluid supplied to an actuator which drives a working device is disclosed. The antitheft system includes reading information on a function selection switch, a timer, a safety lever and engine operation; determining whether the function selection switch is turned on or off; determining whether the safety lever is switched to an OFF position; comparing an input time inputted in a timer with a preset time and if the input time of the timer is shorter than the preset time, proceeding to the step of determining whether the function selection switch is turned on or off; determining whether an ignition of the engine is turned on if the function selection switch is switched to an ON state by a driver, the safety lever is switched to the OFF position by the driver, and the input time of the timer is longer than a preset time; determining that the driver gets out of a cabin in the state in which the ignition of the engine is turned on, and locking the driving unit so that the driving unit does not operate if it is determined that the ignition is turned on; determining whether a security device is passed by the driver if the driving unit is switched to a lock position; and an eighth step of unlocking the driving unit if the user has passed the security device.