The utility model relates to a safety device of a side dump car which is arranged in a lifting control system of the side dump car, and at the rotary spot of the side dump car. The safety device comprises a dog and a pin roll which is inserted in the dog to limit the rotation of the car, and a control switch which closes when the pin roll is detected to be inserted in the dog and opens when the pin roll is detected to be out of the dog. The control switch is a contact switch or a non-contact switch. The control switch is the switch of the gas circuit. The switch of the gas circuit is a stroke control gas valve which is serially integrated between the gas storage container of the lifting control system and a manual gas valve. The adoption of the safety device can prevent the spontaneous lifting during the driving and can prevent the damage caused by lifting without removing the pin roll in the reason of the carelessness of the operating personnel.