Vital component of a pump is the shaft, which serves to continue the torque of the driving during the operation and the seat of the impeller and other rotating parts.This research will be observed and taken action to find the cause of the damage that the sentence is not complete.The results showed that the main cause of damage to the pump shaft submersible because one shaft surfaces that are in the bearings rub against each other to generate heat, consequently between the shaft and the bearing sticking together, so the shaft is stopped suddenly resulting in rows experiencing shock loads (impact load) then the motor continues to rotate, resulting in shaft having torsional force. Because the area is an area that has a radius concentrated high voltage, then the broken shaft in the arearesulted in the remaining of word is not clear a broken pump shaft on oil drilling unit.Examinations and tests performed on the pump shaft, include: fraktografi and metallographic examination and hardness testing. Data from the results of examination and tests are then analyzed to determine the cause of the fracture on the pump shaft.